arm: CPUID is x86-specific

If someone tries to execute CPUID, we fail with an exception.

Signed-off-by: David Scott <dave.scott@citrix.com>
arm: avoid throwing exceptions in non x86 cases

If we can't detect CPU features, return an empty bitmap instead
of throwing an exception. If we can't read the CPU masks from the
commandline, assume all features are masked.

Signed-off-by: David Scott <dave.scott@citrix.com>
Merge pull request #10 from djs55/fix-arm

arm: CPUID is x86-specific