PR tree-optimization/50604

	PR tree-optimization/50604
	* builtins.c (fold_builtin_strcpy, fold_builtin_stpcpy,
	fold_builtin_strncpy, fold_builtin_stxcpy_chk): Ensure
	last argument to memcpy has size_type_node type instead of
	ssizetype.
	* tree-ssa-strlen.c (handle_builtin_memcpy): Use size_type_node
	instead of TREE_TYPE (len) as type for newlen.

	* gcc.dg/pr50604.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@179508 138bc75d-0d04-0410-961f-82ee72b054a4