[BUG] Fix listen & more of 2 couples <ip>:<port>

Fix "listen www-mutualise 80.248.x.y1:80,80.248.x.y2:80,80.248.x.y3:80":

[ALERT] 309/161509 (15450) : Invalid server address: '80.248.x.y1:80,80.248.x.y2'
[ALERT] 309/161509 (15450) : Error reading configuration file : /etc/haproxy/haproxy.cfg

Bug reported by Laurent Dolosor.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index f98d07e..5d70341 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -159,7 +159,7 @@
 
 		str = next;
 		/* 1) look for the end of the first address */
-		if ((next = strrchr(str, ',')) != NULL) {
+		if ((next = strchr(str, ',')) != NULL) {
 			*next++ = 0;
 		}