Use ptid_t.tid to store thread ids instead of ptid_t.pid.

	Use ptid_t.tid to store thread ids instead of ptid_t.pid.

	* win32-nat.c (win32_add_thread): Change thread argument type to
	ptid_t.  Adjust.
	(win32_add_thread): Adjust.
	(win32_delete_thread): Change thread argument type to ptid_t.
	Adjust.
	(win32_fetch_inferior_registers, win32_store_inferior_registers)
	(win32_resume, get_win32_debug_event, get_win32_debug_event)
	(win32_wait, win32_pid_to_exec_file, win32_pid_to_str): Adjust.
	(init_win32_ops): Put to_magic last.
	(win32_win32_thread_alive): Adjust.