builtins.c (expand_builtin): Handle BUILT_IN_INDEX and BUILT_IN_RINDEX.

	* builtins.c (expand_builtin): Handle BUILT_IN_INDEX and
	BUILT_IN_RINDEX.  Add missing checks for BUILT_IN_STRCHR and
	BUILT_IN_STRRCHR.

	* builtins.def (BUILT_IN_INDEX, BUILT_IN_RINDEX): New entries.

	* c-common.c (c_common_nodes_and_builtins): Declare index and
	rindex when nonansi builtins are allowed.

	* extend.texi (index, rindex): Document new builtins.

testsuite:
	* gcc.c-torture/execute/string-opt-3.c: Also test builtin rindex.
	* gcc.c-torture/execute/string-opt-4.c: Also test builtin index.

From-SVN: r37416