c-common.c (check_format_info): Warn for a wide character string used as a non-wide format argument.

	* c-common.c (check_format_info): Warn for a wide character string
	used as a non-wide format argument.

testsuite:
	* gcc.dg/c90-printf-1.c: Add test for wide string format.

From-SVN: r36586