* libc/include/sys/cdefs.h (_Static_assert): Accommodate gcc >= 4.6.
	* libc/ctype/isalnum.c: Correct domain of definition to SUSv4 wording.
	* libc/ctype/isalpha.c: Ditto.
	* libc/ctype/isblank.c: Ditto.
	* libc/ctype/iscntrl.c: Ditto.
	* libc/ctype/isdigit.c: Ditto.
	* libc/ctype/islower.c: Ditto.
	* libc/ctype/isprint.c: Ditto.
	* libc/ctype/ispunct.c: Ditto.
	* libc/ctype/isxdigit.c: Ditto.