Fix: nonadjacent grabber after move

Fix: nonadjacent grabber after move

A monster which has grabbed you could move away without becoming unstuck
if it hit the "move and shoot" or "helpless" conditions in the dochug
MMOVE_MOVED case (since those lead to early return or break), leaving
the hero stuck to a monster which is no longer adjacent.  Put the
'grabber moved away -> become unstuck' stuff at the top of the block so
that it will always be evaluated if a grabber has moved.

I would have liked to move the whole "grabber checks" block up, but I
think it'd change behavior to have the u.uswallow attack come before the
early return for a helpless monster, so I split it up instead.