avcenc: Add bitstream overflow check during emulation prevention am: 10910bf910 am: 51373e847b am: 08e74b410b am: 4e4dc6be01 am: 2c9758d16a

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libavc/+/13932334

Change-Id: Ib9e3a137286a16ebbcd5a38c3a38c0707ada405c