c-common.c (c_common_nodes_and_builtins): Create a cstring_endlink, use it.

c-common.c (c_common_nodes_and_builtins): Create a cstring_endlink, use it.

	* c-common.c (c_common_nodes_and_builtins): Create a
	cstring_endlink, use it.  Rename int_ftype_string_string to
	int_ftype_cstring_cstring, string_ftype_string_int to
	string_ftype_cstring_int, and string_ftype_string_string to
	string_ftype_cstring_cstring.  Prefer sizetype_endlink and
	int_endlink to manually recreating them.  Fix the prototype
	set for __builtin_strspn/__builtin_strcspn.

From-SVN: r38329