Clear hold shelf [expire] time at checkout to alternate patron

Clear hold shelf [expire] time at checkout to alternate patron

When an item on the holds shelf is checked out to an alternate patron
(i.e. not the hold user), clear the shelf_time and shelf_expire_time
along with capture_time, current_copy, etc. on the hold.

tsbere++ for isolating the problem.

Signed-off-by: Bill Erickson <berick@esilibrary.com>