BUG/MINOR: startup: don't fork worker if started with -c -W

Don't do master-worker fork if MODE_CHECK is detected from the command line along
with the master-worker mode. We should exit in MODE_CHECK, after the
configuration parsing and validation. So, with the new master-worker architecture
it's better to align this mode with the standalone.

This patch does not need to be backported, as related to the latest
master-worker rework.

Author: einval22

src/haproxy.c

@@ -3150,6 +3150,12 @@ static void read_cfg_in_discovery_mode(int argc, char **argv)
 		ha_alert("a master CLI socket was defined, but master-worker mode (-W) is not enabled.\n");
 		exit(EXIT_FAILURE);
 	}
+
+	/* in MODE_CHECK and in MODE_DUMP_CFG we just need to parse the
+	 * configuration and exit, see step_init_2()
+	 */
+	if ((global.mode & MODE_MWORKER) && (global.mode & (MODE_CHECK | MODE_DUMP_CFG)))
+		global.mode &= ~MODE_MWORKER;
 }
 
 void deinit(void)