Heap-use-after-free in WelsDec::MapColToList0

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13185

Crash type: Heap-use-after-free READ 4
Crash state:
WelsDec::MapColToList0
WelsDec::ParseInterBMotionInfoCabac
WelsDec::WelsDecodeMbCabacBSliceBaseMode0