xwayland: do not check execve() return value

Simplifies the code a bit.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

compositor/xwayland.c

@@ -285,12 +285,13 @@ spawn_xserver(void *user_data, const char *display, int abstract_fd, int unix_fd
 		if (!ret)
 			_exit(EXIT_FAILURE);
 
-		if (execve(xserver, (char *const *)argv, envp) < 0) {
+		execve(xserver, (char *const *)argv, envp);
+		/* execve does not return on success, so it failed */
+
 		if (exec_failure_msg) {
 			write(STDERR_FILENO, exec_failure_msg,
 			      strlen(exec_failure_msg));
 		}
-		}
 
 		_exit(EXIT_FAILURE);