gdb/

gdb/
	Code cleanup.
	* frame-unwind.c (frame_unwind_find_by_frame): Remove the return type
	and returned value.  New comment from frame-unwind.h.
	* frame-unwind.h (frame_unwind_find_by_frame): Remove the return type.
	Extend the comment.
	* frame.c (get_frame_id, frame_unwind_register_value)
	(create_new_frame, get_prev_frame_1, frame_unwinder_is)
	(get_frame_type, frame_unwind_arch): Do not use the return value of
	frame_unwind_find_by_frame.