x86, cpu: Add a synthetic, always true, cpu feature

This will be used in alternatives later as an always-replace flag.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1370772454-6106-2-git-send-email-bp@alien8.de


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>