bug#12471: Avoid some signal-handling races, and simplify.

[Jan Djärv]

Hello.

19 sep 2012 kl. 01:39 skrev Paul Eggert <eggert@cs.ucla.edu>:

> * Signals are always redirected to the main thread, resulting in
>   incorrect backtraces when, for example, a subsidiary thread has
>   a segmentation violation.  Thread-specific signals like SIGSEGV
>   should have thread-specific backtraces.

and

+       * atimer.c (deliver_alarm_signal):
+       Remove.  No need to deliver this to the parent; any thread can
+       handle this signal now.  All uses replaced by underlying handler.

and

-static void
-deliver_alarm_signal (int sig)
-{
-  handle_on_main_thread (sig, handle_alarm_signal);
-}
-
-
-/* Call alarm signal handler for pending timers.  */

is totally wrong.  Thread sarted by Gnome/gtk+ plugins can not handle SIGALRM, 
so Emacs will terminate.   This is the reason for this in the first place. 
Don't install this and other stuff that removes redirecting signals to the main 
thread.

        Jan D.