MINOR: sample: add a new CFG_PARSER context for samples

We'd sometimes like to be able to process samples while parsing
the configuration based on purely internal thing but that's not
possible right now. Let's add a new CFG_PARSER context for samples
which only permits constant samples (i.e. those which do not change
in the process' life and which are stable during config parsing).
diff --git a/src/sample.c b/src/sample.c
index 1b2abfd..5b78125 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -76,7 +76,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL_CFG_PARSER),
 
 	[SMP_SRC_INTRN] = (SMP_VAL_FE_CON_ACC | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -84,7 +84,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_LISTN] = (SMP_VAL_FE_CON_ACC | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -92,7 +92,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_FTEND] = (SMP_VAL_FE_CON_ACC | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -100,7 +100,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_L4CLI] = (SMP_VAL_FE_CON_ACC | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -108,7 +108,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_L5CLI] = (SMP_VAL___________ | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -116,7 +116,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_TRACK] = (SMP_VAL_FE_CON_ACC | SMP_VAL_FE_SES_ACC | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -124,7 +124,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_L6REQ] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -132,7 +132,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL___________ | SMP_VAL___________),
+	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_HRQHV] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -140,7 +140,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL___________ | SMP_VAL___________),
+	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_HRQHP] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_FE_REQ_CNT |
 	                   SMP_VAL_FE_HRQ_HDR | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -148,7 +148,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_HRQBO] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL_FE_HRQ_BDY | SMP_VAL_FE_SET_BCK |
@@ -156,7 +156,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL___________ | SMP_VAL___________),
+	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_BKEND] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -164,7 +164,7 @@
 	                   SMP_VAL_BE_SET_SRV | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_SERVR] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -172,7 +172,7 @@
 	                   SMP_VAL___________ | SMP_VAL_BE_SRV_CON | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_L4SRV] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -180,7 +180,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_L5SRV] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -188,7 +188,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_L6RES] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -196,7 +196,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_HRSHV] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -204,7 +204,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_HRSHP] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -212,7 +212,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL_BE_RES_CNT |
 	                   SMP_VAL_BE_HRS_HDR | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_HRSBO] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -220,7 +220,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL_BE_HRS_BDY | SMP_VAL_BE_STO_RUL |
 	                   SMP_VAL_FE_RES_CNT | SMP_VAL_FE_HRS_HDR | SMP_VAL_FE_HRS_BDY |
-	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL),
+	                   SMP_VAL___________ | SMP_VAL_BE_CHK_RUL | SMP_VAL___________),
 
 	[SMP_SRC_RQFIN] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -228,7 +228,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_RSFIN] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -236,7 +236,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_TXFIN] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -244,7 +244,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 
 	[SMP_SRC_SSFIN] = (SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
@@ -252,7 +252,7 @@
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
 	                   SMP_VAL___________ | SMP_VAL___________ | SMP_VAL___________ |
-	                   SMP_VAL_FE_LOG_END | SMP_VAL___________),
+	                   SMP_VAL_FE_LOG_END | SMP_VAL___________ | SMP_VAL___________),
 };
 
 static const char *fetch_src_names[SMP_SRC_ENTRIES] = {