Announce thread death on MS-Windows.

Announce thread death on MS-Windows.

	* windows-nat.c (windows_delete_thread): Accept an additional
	argument, the thread's exit code, and announce thread death when
	print_thread_events is non-zero and we are deleting a thread that
	is not the main thread.
	(get_windows_debug_event): Pass thread exit code to
	windows_delete_thread.