[CLEANUP] Move counters to dedicated structures

Move counters from "struct proxy" and "struct server"
to "struct pxcounters" and "struct svcounters".

This patch should make no functional change.
diff --git a/include/types/server.h b/include/types/server.h
index 3304004..ddf5a46 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -30,6 +30,7 @@
 #include <common/mini-clist.h>
 
 #include <types/buffers.h>
+#include <types/counters.h>
 #include <types/freq_ctr.h>
 #include <types/port_range.h>
 #include <types/proxy.h>
@@ -119,24 +120,17 @@
 	struct eb_root *lb_tree;                /* we want to know in what tree the server is */
 	struct server *next_full;               /* next server in the temporary full list */
 
-	long long failed_checks, down_trans;	/* failed checks and up-down transitions */
 	unsigned down_time;			/* total time the server was down */
 	time_t last_change;			/* last time, when the state was changed */
 	struct timeval check_start;		/* last health check start time */
 	unsigned long check_duration;		/* time in ms took to finish last health check */
 	short check_status, check_code;		/* check result, check code */
 
-	long long failed_conns, failed_resp;	/* failed connect() and responses */
-	long long retries, redispatches;	/* retried and redispatched connections */
-	long long failed_secu;			/* blocked responses because of security concerns */
 	struct freq_ctr sess_per_sec;		/* sessions per second on this server */
 	unsigned int sps_max;			/* maximum of new sessions per second seen on this server */
-	long long cum_sess;			/* cumulated number of sessions really sent to this server */
-	long long cum_lbconn;			/* cumulated number of sessions directed by load balancing */
-
-	long long bytes_in;			/* number of bytes transferred from the client to the server */
-	long long bytes_out;			/* number of bytes transferred from the server to the client */
 	int puid;				/* proxy-unique server ID, used for SNMP */
+
+	struct srvcounters counters;		/* statistics counters */
 };