OSV-2018-46 Heap-buffer-overflow in GDAL_LercNS::RLE::readCount

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=9282 Crash type: Heap-buffer-overflow READ 2 Crash state: GDALLercNS::RLE::readCount GDALLercNS::RLE::decompress GDALLercNS::Lerc2::ReadMask...