BUG/MINOR: server: dont return immediately from parse_server() when skipping checks

If parse_server() is called under peers section parser, and the address
needs to be parsed but it is missing, we directly return from the function

However since 0fc136ce5b ("REORG: server: use parsing ctx for server
parsing"), parse_server() uses parsing ctx to emit warning/errors, and
the ctx must be reset before returning from the function, yet this early
return was overlooked. Because of that, any ha_{warning,alert..} message
reported after early return from parse_server() could cause messages to
have an extra "parsing [file:line]" info.

We fix that by ensuring parse_server() doesn't return without resetting
the parsing context.

It should be backported up to 2.6

src/server.c

@@ -3758,7 +3758,7 @@ int parse_server(const char *file, int linenum, char **args,
 	if ((parse_flags & (SRV_PARSE_IN_PEER_SECTION|SRV_PARSE_PARSE_ADDR)) ==
 	    (SRV_PARSE_IN_PEER_SECTION|SRV_PARSE_PARSE_ADDR)) {
 		if (!*args[2])
-			return 0;
+			goto out;
 	}
 
 	err_code = _srv_parse_init(&newsrv, args, &cur_arg, curproxy,