constify some cli-utils stuff

constify some cli-utils stuff

This constifies a few functions in cli-utils -- get_number_trailer and
friends -- and then fixes the fallout.

2014-07-30  Tom Tromey  <tromey@redhat.com>

	* breakpoint.c (map_breakpoint_numbers): Update.
	* cli/cli-utils.c (get_number_trailer): Make "pp" const.  Update.
	(get_number_const): New function.
	(get_number): Rewrite using get_number_const.
	(init_number_or_range): Make "string" const.
	(number_is_in_list): Make "list" const.
	* cli/cli-utils.h (get_number_const): Declare.
	(struct get_number_or_range_state) <string, end_ptr>: Now const.
	(init_number_or_range, number_is_in_list): Update.
	* printcmd.c (map_display_numbers): Update.
	* value.c (value_from_history_ref): Constify.
	* value.h (value_from_history_ref): Update.