[MEDIUM] errorloc now checked first from backend then from frontend

It is now possible to define an errorloc in the backend as well as
in the frontend. The backend's will be used first, and if undefined,
then the frontend's will be used instead. If none is used, then the
original error messages will be used.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index f3659f5..d707685 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -1740,7 +1740,7 @@
 	char *args[MAX_LINE_ARGS];
 	int arg;
 	int cfgerr = 0;
-	int nbchk, mininter, rc;
+	int nbchk, mininter;
 	int confsect = CFG_NONE;
 
 	struct proxy *curproxy = NULL;
@@ -2029,17 +2029,6 @@
 		if (curproxy->options & PR_O_LOGASAP)
 			curproxy->to_log &= ~LW_BYTES;
 
-		for (rc = 0; rc < HTTP_ERR_SIZE; rc++) {
-			if (!http_err_msgs[rc]) {
-				Alert("Internal error: no message defined for HTTP return code %d. Aborting.\n");
-				abort();
-			}
-			if (!curproxy->errmsg[rc].str) {
-				curproxy->errmsg[rc].str = strdup(http_err_msgs[rc]);
-				curproxy->errmsg[rc].len = strlen(http_err_msgs[rc]);
-			}
-		}
-
 		/*
 		 * If this server supports a maxconn parameter, it needs a dedicated
 		 * tasks to fill the emptied slots when a connection leaves.