OSV-2020-736 Heap-use-after-free in WelsDec::DecreasePicBuff

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14423 Crash type: Heap-use-after-free READ 8 Crash state: WelsDec::DecreasePicBuff WelsRequestMem SyncPictureResolutionExt...