Add some more CTL_FLAG_ABORT check points.

This should allow to abort commands doing mostly disk I/O, such as VERIFY
or WRITE SAME.  Before this change CTL_FLAG_ABORT was only checked around
data moves, which for these commands may not happen for a very long time.

MFC after:	2 weeks

(cherry picked from commit 281c52cb4ab2605c738c2893bcc3cb395489dabc)