ubik: Abstract buffer matching and pass trans ptrs

ubik: Abstract buffer matching and pass trans ptrs

Abstract the code for matching buffers in DRead, and pass around
ubik_trans pointers instead of ubik_dbase pointers. This changes no
behavior, but makes changing ubik buffer code a bit easier.

Reviewed-on: http://gerrit.openafs.org/2230
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 5c7297a6c76777aec6209aa191b067ddc73b1a87)

Change-Id: I6cc673d965b5e06361fff8ea259ba552446e3213
Reviewed-on: http://gerrit.openafs.org/6259
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>