block/iscsi: fix deadlock on scsi check condition

the retry logic was broken because the complete status
of the task structure was not reset. this resulted in
an infinite loop retrying the command over and over.

CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
block/iscsi: fix segfault if writesame fails

commit fa6252b0 introduced a segfault because it tries
to read iTask.task->sense after iTask.task has been
freed.

CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
block/vmdk: do not report file offset for compressed extents

Signed-off-by: Peter Lieven <pl@kamp.de>