OSV-2024-1149 Use-of-uninitialized-value in ultrahdr::uhdr_gainmap_metadata_frac::encodeGainmapMetadata

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=369652657 Crash type: Use-of-uninitialized-value Crash state: ultrahdr::uhdrgainmapmetadatafrac::encodeGainmapMetadata ultrahdr::JpegR::appendGainMap ultrahdr::JpegR::encodeJPEGR...