Implement the MSRs ignore unknown reads and writes feature
that's specified using:
<features>
...
<msrs unknown='ignore'>
...
</features>
in the domain XML.
In bhyve, it's just passing '-w' command line argument to the bhyve(8)
executable.
Signed-off-by: Roman Bogorodskiy <bogorodskiy@gmail.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
