migration: Test for disabled features on reception

Right now, if we receive a compressed page while this features are
disabled, Bad Things (TM) can happen.  Just add a test for them.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>

--

I had XBZRLE here also, but it don't need extra resources on
destination, only on source.  Additionally libvirt don't enable it on
destination, so don't put it here.

- initialize invalid_flags at declaration time.
- remove extra space (peter)
