Make sure all CPUID values are handled, instead of exiting the
bhyve process when an unhandled one is encountered.

Hide some additional capabilities from the guest (e.g. debug store).

This fixes the issue with FreeBSD 9.1 MP guests exiting the VM on
AP spinup (where CPUID is used when sync'ing the TSCs) and the
issue with the Java build where CPUIDs are issued from a guest
userspace.

Submitted by: tycho nightingale at pluribusnetworks com
Reviewed by: neel
Reported by: many