* exceptions.cc (INIT_EXCEPTION_HANDLER): Eliminate.

(init_exceptions): Just use init_exception_handler.
(open_stackdumpfile): New function.
(stack_info::first_time): Eliminate.
(stack_info::init): Set up fields to avoid "first_time" consideration.
(stack_info::walk): Remove "first_time" consideration.
(stackdump): Change arguments to accept initial frame pointer and open stack
file flag.
(stack): Eliminate.
(cygwin_stackdump): Use stackdump() rather than stack().
(try_to_debug): Remove all synchronization logic.  Just keep looping in
exception handler until debugger notices us.  Return 1 if successfully started
debugger.
(handle_exceptions): Just return if we know that we're debugging.  Reorganize
to avoid creating a stackdump file if we are starting a debugger.  Return from
exception handler if debugger started successfully.
(sig_handle): Create a stackdump only if debugger wasn't started.
* winsup.h (try_to_debug): Add an argument.

winsup/cygwin/winsup.h

@@ -184,7 +184,7 @@ extern HANDLE netapi32_handle;
 
 /* debug_on_trap support. see exceptions.cc:try_to_debug() */
 extern "C" void error_start_init (const char*);
-extern "C" int try_to_debug ();
+extern "C" int try_to_debug (bool waitloop = 1);
 
 extern int cygwin_finished_initializing;