* defs.h (add_inferior_continuation)

	* defs.h (add_inferior_continuation)
	(do_all_inferior_continuations)
	(discard_all_inferior_continuations): Declare.
	* utils.c (add_inferior_continuation)
	(do_all_inferior_continuations)
	(discard_all_inferior_continuations): New.
	* inferior.h (struct inferior) <continuations>: New field.
	* inferior.c (free_inferior): Discard all the inferior
	continuations.
	* inf-loop.c (inferior_event_handler): Do all current inferior
	continuations.
	* infcmd.c (attach_command): Register an inferior continuation
	instead of a thread continuation.
	* infrun.c (handle_inferior_event): If stop_soon is
	STOP_QUIETLY_NO_SIGSTOP, also expect a TARGET_SIGNAL_0.