Revert "xwayland: Reset signal mask and handlers before exec"

This reverts commit 954dba3968.

Motivations:

- This only resets some state, but other global state such as other
  signal handlers, process limits (e.g. NOFILE) or system-specific
  settings are left as-is. The chunk of state which does get reset
  is opinionated.
- Compositors have other ways to do this, e.g. with pthread_atfork()
  or with empty signal handler callbacks.

xwayland/server.c

@@ -36,13 +36,6 @@ noreturn static void exec_xwayland(struct wlr_xwayland_server *server,
 		_exit(EXIT_FAILURE);
 	}
 
-	// The compositor may have messed with signal handling, try to clean it up
-	sigset_t set;
-	sigemptyset(&set);
-	sigprocmask(SIG_SETMASK, &set, NULL);
-	signal(SIGPIPE, SIG_DFL);
-	signal(SIGCHLD, SIG_DFL);
-
 	char *argv[64] = {0};
 	size_t i = 0;