OSV-2018-388 Use-of-uninitialized-value in MatShaperEval16

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5748 Crash type: Use-of-uninitialized-value Crash state: MatShaperEval16 PrecalculatedXFORM cmsDoTransform...