Merge "BufferPool: limit number of idle buffers in caches" am: 4a76ebecce am: 55df06adf3

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/1526345

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I6e5a080613c13bac6348536e0c51eb9eb96edd79