Add correct variable names for _POSIX_IPV6 and _POSIX_RAW_SOCKETS

getconf only recognizes IPV6 and RAW_SOCKETS, when the standard
requires it to recognize the actual configuration variable name[1].  I
have not removed the earlier names for compatibility.

	* posix/getconf.c (vars): Add _POSIX_IPV6 and
	_POSIX_RAW_SOCKETS.

[1] http://pubs.opengroup.org/onlinepubs/007904875/functions/sysconf.html