* linux-nat.c (struct simple_pid_list): Add status.

	* linux-nat.c (struct simple_pid_list): Add status.
	(add_to_pid_list): Record the PID's status.
	(linux_record_stopped_pid): Likewise.  Make static.
	(pull_pid_from_list): Return the saved status.
	(linux_nat_handle_extended): Deleted.
	(linux_handle_extended_wait): Combine with linux_nat_handle_extended.
	Make static.  Handle non-SIGSTOP for a new thread's first signal.
	(flush_callback): Handle unexpected pending signals.
	(linux_nat_wait): Update calls to changed functions.
	* linux-nat.h (linux_record_stopped_pid, linux_handle_extended_wait):
	Remove prototypes for newly static functions.

	* gdb.threads/sigthread.c, gdb.threads/sigthread.exp: New.