MINOR: proxy: Add references on http replies for proxy error messages

Error messages defined in proxy section or inherited from a default section are
now also referenced using an array of http replies. This is done during the
configuration validity check.
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 35ca0ad..62fc435 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -409,6 +409,7 @@
 	char *check_command;			/* Command to use for external agent checks */
 	char *check_path;			/* PATH environment to use for external agent checks */
 	struct buffer *errmsg[HTTP_ERR_SIZE];	/* default or customized error messages for known errors */
+	struct http_reply *replies[HTTP_ERR_SIZE]; /* HTTP replies for known errors */
 	int uuid;				/* universally unique proxy ID, used for SNMP */
 	unsigned int backlog;			/* force the frontend's listen backlog */
 	unsigned long bind_proc;		/* bitmask of processes using this proxy */
diff --git a/src/http_htx.c b/src/http_htx.c
index b830c73..18ac47c 100644
--- a/src/http_htx.c
+++ b/src/http_htx.c
@@ -1852,6 +1852,7 @@
 			/* errorfile */
 			rc = http_get_status_idx(conf_err->info.errorfile.status);
 			px->errmsg[rc] = conf_err->info.errorfile.msg;
+			px->replies[rc] = conf_err->info.errorfile.reply;
 		}
 		else {
 			/* errorfiles */
@@ -1872,8 +1873,10 @@
 			free(conf_err->info.errorfiles.name);
 			for (rc = 0; rc < HTTP_ERR_SIZE; rc++) {
 				if (conf_err->info.errorfiles.status[rc] > 0) {
-					if (http_errs->errmsg[rc])
+					if (http_errs->errmsg[rc]) {
 						px->errmsg[rc] = http_errs->errmsg[rc];
+						px->replies[rc] = http_errs->replies[rc];
+					}
 					else if (conf_err->info.errorfiles.status[rc] == 2)
 						ha_warning("config: proxy '%s' : status '%d' not declared in"
 							   " http-errors section '%s' (at %s:%d).\n",
@@ -1934,6 +1937,7 @@
 		if (conf_err->type == 1) {
 			new_conf_err->info.errorfile.status = conf_err->info.errorfile.status;
 			new_conf_err->info.errorfile.msg    = conf_err->info.errorfile.msg;
+			new_conf_err->info.errorfile.reply  = conf_err->info.errorfile.reply;
 		}
 		else {
 			new_conf_err->info.errorfiles.name = strdup(conf_err->info.errorfiles.name);