* builtins.def (BUILT_IN_STPNCPY_CHK): New definition.
	* builtins.c (expand_builtin, fold_builtin_4, maybe_emit_chk_warning):
	Add BUILT_IN_STPNCPY_CHK case.
	* gimple-fold.c (gimple_fold_builtin): Likewise.
	* tree-object-size.c (pass_through_call): Likewise.
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1,
	call_may_clobber_ref_p_1): Likewise.
	* tree-ssa-structalias.c (find_func_aliases_for_builtin_call,
	find_func_clobbers): Likewise.
	* tree.h (fold_builtin_strncpy_chk): Rename to fold_builtin_stxncpy_chk
	* builtins.c (fold_builtin_strncpy_chk): Likewise.
	Rewrite stpncpy_chk calls to strncpy_chk calls if returned value is
	ignored.

	* gcc.c-torture/execute/builtins/chk.h (stpncpy, stpncpy_disallowed):
	New definitions.
	* gcc.c-torture/execute/builtins/lib/chk.c (stpncpy_disallowed):
	Likewise.
	(stpncpy, __stpncpy_chk): New functions.
	* gcc.c-torture/execute/builtins/stpncpy-chk-lib.c: New file.
	* gcc.c-torture/execute/builtins/stpncpy-chk.c: Likewise.

From-SVN: r182378