Merge "Decoder: add support for KEEP_THREADS_ACTIVE" am: eb0e6acc60 am: 33be8ea9ce am: 795d9f12e6

Original change: https://android-review.googlesource.com/c/platform/external/libmpeg2/+/1740742

Change-Id: Ia1aaf9c09accfd216b9b54cc666d02cbe7fa4a90