virtio: add low-level APIs for feature bits
virtio: add low-level APIs for feature bits

Add low level APIs to test/set/clear feature bits.
For use by transports, to make it easier to
write code independent of feature bit array format.

Note: APIs is prefixed with __ and has _bit suffix
to stress its low level nature.  It's for use by transports only:
drivers should use virtio_has_feature and never need to set/clear
features.

Signed-off-by: Michael S. Tsirkin <255103e50249e3d658441816e0597170ebfc16ef@redhat.com>
Reviewed-by: Cornelia Huck <94980dd689360e06f79e918bf71ea5fed7a2bc63@de.ibm.com>





KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs