BufferQueue: Allow detaching/reattaching buffers

Adds detachBuffer and attachBuffer calls to both the producer and
consumer sides of BufferQueue. Buffers may be detached while dequeued
by the producer or acquired by the consumer, and when attached, enter
the dequeued and acquired states, respectively.

Bug: 13173343
Change-Id: Ic152692b0a94d99e0135b9bfa62747dab2a54220
14 files changed