OSV-2020-2297 Heap-double-free in WelsCommon::WelsFree

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=29073 Crash type: Heap-double-free Crash state: WelsCommon::WelsFree WelsCommon::CMemoryAlign::WelsFree WelsDec::FreePicture...