signals: let the default handlers kill VLC after 3 seconds

This should only be used if VLC deadlocks, or takes an awfully long time
to clean up. That will let VLC be killed as with the older signals
handler.

modules/control/signals.c

@@ -88,6 +88,7 @@ static void *SigThread (void *data)
 {
     intf_thread_t *obj = data;
     sigset_t set;
+    int signum;
 
     sigemptyset (&set);
     sigaddset (&set, SIGHUP);
@@ -97,10 +98,8 @@ static void *SigThread (void *data)
 
     sigaddset (&set, SIGCHLD);
 
-    for (;;)
+    do
     {
-        int signum;
-
         sigwait (&set, &signum);
 
 #ifdef __APPLE__
@@ -108,17 +107,15 @@ static void *SigThread (void *data)
          * cancellation point */
         vlc_testcancel();
 #endif
-
-        switch (signum)
-        {
-            case SIGINT:
-            case SIGHUP:
-            case SIGTERM:
-            case SIGQUIT:
-                msg_Err (obj, "Caught %s signal, exiting...",
-                         strsignal (signum));
-                libvlc_Quit (obj->p_libvlc);
-                break;
-        }
     }
+    while (signum == SIGCHLD);
+
+    msg_Err (obj, "Caught %s signal, exiting...", strsignal (signum));
+    libvlc_Quit (obj->p_libvlc);
+
+    /* After 3 seconds, fallback to normal signal handling */
+    msleep (3 * CLOCK_FREQ);
+    pthread_sigmask (SIG_UNBLOCK, &set, NULL);
+    for (;;)
+        pause ();
 }