Introduce common cleanup for restoring integers.

	Introduce common cleanup for restoring integers.
        * defs.h (make_cleanup_restore_integer): New declaration.
        (struct cleanup): New field free_arg.
        (make_my_cleanup_2): New.
        * utils.c (restore_integer_closure, restore_integer)
        (make_cleanup_restore_integer): New.
        (make_my_cleanup): Initialize the free_arg field and
        renamed to make_my_cleanup_2.
        (do_my_cleanups): Call free_arg.
        (discard_cleanups): Call free_arg.
        * breakpoint.c (restore_always_inserted_mode): Remove.
        (update_breakpoints_after_exec): Use make_cleanup_restore_integer.