Introduce TYPE_ constant and cast macro.
Move the state struct to the new header to allow for future embedding.
Signed-off-by: NAndreas Färber <andreas.faerber@web.de>
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>