Camera3: fix aborting reprocess requests

Get an input buffer right after camera service takes one
reprocess capture request from the request queue to prevent
the input buffers getting out of order.

When aborting pending reprocess requests in the request queue, also
abort the same amount of input buffers.

Bug: 21028914
Change-Id: I7cfacecb4c24509f59c983abd587db5a403237bd