qapi: add transaction support for x-block-dirty-bitmap-merge

New action is like clean action: do the whole thing in .prepare and
undo in .abort. This behavior for bitmap-changing actions is needed
because backup job actions use bitmap in .prepare.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
2 files changed