The test for fpu transition will require to do
a runtime check for the cpu features it's running
on. For this sake we need to use cpuid. Thus make
it more widely available by providing in the general
header.

The code is adopted from the linux kernel code.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>