OSV-2020-2115 Use-of-uninitialized-value in DeblockChromaLt42_c

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26758 Crash type: Use-of-uninitialized-value Crash state: DeblockChromaLt42c DeblockChromaLt4V2c WelsDec::FilteringEdgeChromaH...