avcenc: Add bitstream overflow check during emulation prevention

Bug: 176533109

Test: poc in the bug description

Change-Id: Ia83383f9b65cbde8d7a50a1af8a054936daa4d78
(cherry picked from commit b59de5a25f28f0fe411526b2e50bb8052957c517)
(cherry picked from commit 10910bf9106eff724390255faa48f9f61dcfc744)
5 files changed