qemu_monitor: Filter CPU features reported by QEMU

qemu_monitor: Filter CPU features reported by QEMU

Some features may be on our ignore list because they do nothing even
though QEMU still supports them and reports their state. But as the
features do nothing, the state reported by QEMU may not correspond to
what the guest sees. To avoid possible confusion we may just pretend
QEMU did not report any of the features on our ignore list.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>