* c-common.c (FMT_FLAG_ARG_CONVERT, FMT_FLAG_SCANF_A_KLUDGE,
	FMT_FLAG_FANCY_PERCENT_OK): Define.
	(format_char_info): Add flag "4" to comment.
	(format_flag_spec, format_flag_pair): New structures.
	(format_kind_info): Add additional fields to control format
	checking.
	(printf_flag_specs, printf_flag_pairs, scanf_flag_specs,
	scanf_flag_pairs, strftime_flag_specs, strftime_flag_pairs): New
	arrays.
	(time_char_table): Use "4" flag to handle %Ey.
	(format_types): Add entries for new fields.
	(get_flag_spec): New function.
	(check_format_info): Increase size of flag_chars[] to 256.
	Control format checking using the new fields of a format_kind_info
	and the new tables; remove all conditionals on printf_format_type,
	scanf_format_type or strftime_format_type.  Handle all details of
	bad combinations of flags (including width, precision and strftime
	modifiers) through data rather than ad hoc code.  Handle all
	details of standard versions in which flags appeared through
	data.  Use the "4" flag.

testsuite:
	* gcc.dg/c90-printf-1.c, gcc.dg/c90-scanf-1.c,
	gcc.dg/c99-printf-1.c, gcc.dg/c99-scanf-1.c,
	gcc.dg/c99-strftime-1.c, gcc.dg/format-ext-3.c: Adjust error
	regexps and details of expected handling of some bad formats.
	* gcc.dg/format-xopen-1.c: Add test for $ format with assignment
	suppression.

From-SVN: r36790