Allow to disable buffer dropping from BufferQueueProducer

This makes commit e3c87346e82aeaeed7f91e6b93351b16362debd5 opt-in.

Also reworked this to do this on the looper vs the calling process to
avoid any race conditions.

Bug: 135390389
Change-Id: I9df20f1e60f0bd4ac4f8d8e7b5f02919b170682e
2 files changed