toplev.c (decode_g_option): Don't give warning for unknown -g option; return 0 instead.

toplev.c (decode_g_option): Don't give warning for unknown -g option; return 0 instead.

	* toplev.c (decode_g_option): Don't give warning for unknown -g
	option; return 0 instead.
	(main): If -g option is not recognized by front end or
	language-independent code, give warning.

From-SVN: r36020