MINOR: server: introduction of 3 new server flags

Introduction of 3 new server flags to remember if some parameters were set
during configuration parsing.

* SRV_F_CHECKADDR: this server has a check addr configured
* SRV_F_CHECKPORT: this server has a check port configured
* SRV_F_AGENTADDR: this server has a agent addr configured
diff --git a/include/types/server.h b/include/types/server.h
index 952671c..ce13820 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -98,6 +98,9 @@
 #define SRV_F_NON_STICK    0x0004        /* never add connections allocated to this server to a stick table */
 #define SRV_F_USE_NS_FROM_PP 0x0008      /* use namespace associated with connection if present */
 #define SRV_F_FORCED_ID    0x0010        /* server's ID was forced in the configuration */
+#define SRV_F_CHECKADDR    0x0020        /* this server has a check addr configured */
+#define SRV_F_CHECKPORT    0x0040        /* this server has a check port configured */
+#define SRV_F_AGENTADDR    0x0080        /* this server has a agent addr configured */
 
 /* configured server options for send-proxy (server->pp_opts) */
 #define SRV_PP_V1          0x0001        /* proxy protocol version 1 */
diff --git a/src/server.c b/src/server.c
index e41afc7..a90ae9b 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1002,6 +1002,8 @@
 
 			newsrv->check.use_ssl	= curproxy->defsrv.check.use_ssl;
 			newsrv->check.port	= curproxy->defsrv.check.port;
+			if (newsrv->check.port)
+				newsrv->flags |= SRV_F_CHECKPORT;
 			newsrv->check.inter	= curproxy->defsrv.check.inter;
 			newsrv->check.fastinter	= curproxy->defsrv.check.fastinter;
 			newsrv->check.downinter	= curproxy->defsrv.check.downinter;
@@ -1292,10 +1294,13 @@
 				}
 
 				newsrv->check.addr = newsrv->agent.addr = *sk;
+				newsrv->flags |= SRV_F_CHECKADDR;
+				newsrv->flags |= SRV_F_AGENTADDR;
 				cur_arg += 2;
 			}
 			else if (!strcmp(args[cur_arg], "port")) {
 				newsrv->check.port = atol(args[cur_arg + 1]);
+				newsrv->flags |= SRV_F_CHECKPORT;
 				cur_arg += 2;
 			}
 			else if (!defsrv && !strcmp(args[cur_arg], "backup")) {