block: add bdrv_set_dirty()/bdrv_reset_dirty() to block_int.h The dirty bitmap functions are called from the block I/O processing code. Make them visible to block_int.h users so they can be used outside block.c. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>