* cygerrno.h (set_errno): Set global errno whenever setting thread specific

version.
* debug.cc (__set_errno): Ditto.
* exceptions.cc (handle_sigsuspend): Remove spurious sig_dispatch_pending call.
(set_signal_mask): When there seem to be pending signals to dispatch, tell
signal_dispatch_pending/sig_send not to specifically call any handlers.
* sigproc.h (sig_dispatch_pending): Change declaration to void.
* sigproc.cc (sig_dispatch_pending): Change definition to void.  Take an
argument to determine whether to tell sig_send to wait for handler to be
called.
* sigproc.cc (sig_send): Don't call signal handler when sig == __SIGFLUSHFAST.
(wait_sig): Honor __SIGFLUSHFAST.  Guard against sigpacket::process nuking
si_signo.
* sigproc.h (__SIGFLUSHFAST): Define new special signal.
(sig_dispatch_pending): Change declaration to void.  Take optional boolean
argument.
* fork.cc (vfork): Add debugging output.

winsup/cygwin/debug.cc

@@ -237,6 +237,7 @@ int __stdcall
 __set_errno (const char *func, int ln, int val)
 {
   debug_printf ("%s:%d val %d", func, ln, val);
+  _impure_ptr->_errno = val;
   return errno = val;
 }
 #endif /*DEBUGGING*/