This patch implements __get_cpuid_max() as an inline and __cpuid()
and __cpuid_count() as macros to be compatible with GCC's cpuid.h.
It also adds bit_<foo> constants for the various feature bits as
described in version 039 (May 2011) of Intel's SDM Volume 2 in the
description of the CPUID instruction. The list of bit_<foo>
constants is a bit exhaustive (GCC doesn't do near this many). More
bits could be added from a newer version of SDM if desired.
Patch by John Baldwin!
This should fix several ports which depend on this functionality being
available.
MFC after: 1 week
12ebae77ad