* signal.cc (_raise): New function.

* exceptions.cc (unused_sig_wrapper): Remove _raise.
* sigproc.h (class sigframe): Default frames to skip to zero or suffer from
exuberant optimization.
* fhandler_tty.cc (fhandler_tty::write): Set appropriate errno when WriteFile
to pipe fails.

winsup/cygwin/sigproc.h

@@ -60,7 +60,7 @@ public:
   }
 
   sigframe () {st = NULL;}
-  sigframe (sigthread &t, int up = 1)
+  sigframe (sigthread &t, int up = 0)
   {
     if (!t.frame && t.id == GetCurrentThreadId ())
       set (t, up);