common.opt: Add debug switches.

common.opt: Add debug switches.

	* common.opt: Add debug switches.
	* flags.h (use_gnu_debug_info_extensions): Boolify.
	* opts.c (write_symbols, debug_info_level,
	use_gnu_debug_info_extensions): Move from toplev.c.
	(set_debug_level): New.
	(common_handle_options): Handle debug switches.
	(print_help): Display target options directly.
	* toplev.c (debug_hooks): Don't initialize.
	(write_symbols, debug_info_level,
	use_gnu_debug_info_extensions): Move to opts.c.
	(debug_args, display_help, decode_g_option): Remove.
	(process_options): Set no debug if level zero here,
	and no-debug-hooks.  Error here if impossible debug format selected.
	* toplev.h (display_help, decode_g_option): Remove.
testsuite:
	* lib/gcc-dg.exp: Update for diagnostic change.

From-SVN: r70253