* builtins.c (fold_builtin_isdigit): New.
	(fold_builtin): Handle BUILT_IN_ISDIGIT.
	* defaults.h: Add TARGET_DIGIT0 and sort.
	* doc/tm.texi: Add TARGET_BS and TARGET_DIGIT0.

testsuite:
	* gcc.dg/torture/builtin-ctype-2.c: Test builtin isdigit.

From-SVN: r80681