OSV-2020-2064 Heap-buffer-overflow in WelsDec::DoErrorConSliceCopy

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26285 Crash type: Heap-buffer-overflow WRITE 8 Crash state: WelsDec::DoErrorConSliceCopy WelsDec::ImplementErrorCon WelsDec::CheckAndFinishLastPic...