make the container exit code propagate to lxc-start exit code when appropriate

src/lxc/lxc_start.c

@@ -336,6 +336,9 @@ int main(int argc, char *argv[])
 			ERROR("To get more details, run the container in foreground mode.");
 		ERROR("Additional information can be obtained by setting the "
 		      "--logfile and --log-priority options.");
+		err = c->error_num;
+		lxc_container_put(c);
+		return err;
 	}
 
 out:

src/lxc/lxccontainer.c

@@ -669,6 +669,7 @@ static bool lxcapi_start(struct lxc_container *c, int useinit, char * const argv
 reboot:
 	conf->reboot = 0;
 	ret = lxc_start(c->name, argv, conf, c->config_path);
+	c->error_num = ret;
 
 	if (conf->reboot) {
 		INFO("container requested reboot");