Add mi_getopt_allow_unknown

Add mi_getopt_allow_unknown

This patch is to add a new function mi_getopt_allow_unknown, which
returns -1 silently (without throwing error) when unknown option is
met, and use this function to parse options for command
'-stack-list-arguments'.

gdb/
	* mi/mi-cmd-stack.c (parse_no_frames_option): Remove.
	(mi_cmd_stack_list_args): Use mi_getopt_silent to handle
	options.
	* mi/mi-getopt.c (mi_getopt): Remove.
	(mi_getopt_1): Renamed from mi_getopt.  Add one parameter
	'error_on_unknown'.
	(mi_getopt): Call mi_getopt_1.
	(mi_getopt_silent): New.
	* mi/mi-getopt.h (mi_getopt_silent): Declare.