* exceptions.cc (setup_handler): Add debugging output. Set thread priority to

idle if pending signals to allow other threads to get into interruptible state.
* miscfuncs.cc (sys_mbstowcs): Save current thread in variable to avoid an OS
call.
* wait.cc (wait_sig): Reset thread priority each time through loop since the
priority may have been set down to deal with pending signals.

winsup/cygwin/sigproc.cc

@@ -1096,6 +1096,7 @@ wait_sig (VOID *self)
   for (;;)
     {
       DWORD rc = WaitForMultipleObjects (3, catchem, FALSE, sig_loop_wait);
+      (void) SetThreadPriority (GetCurrentThread (), WAIT_SIG_PRIORITY);
 
       /* sigproc_terminate sets sig_loop_wait to zero to indicate that
        * this thread should terminate.