OSV-2020-654 Heap-buffer-overflow in ZSTD_copy16

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=17451 Crash type: Heap-buffer-overflow READ 16 Crash state: ZSTDcopy16 ZSTDdecompressSequencesbmi2 ZSTDdecompressBlockinternal...