opencv/imread_fuzzer: Use-of-uninitialized-value in cv::PAMDecoder::readHeader

Detailed report: https://oss-fuzz.com/testcase?key=5128776439037952 Project: opencv Fuzzer: libFuzzerimreadfuzzer Fuzz target binary: imreadfuzzer Job Type: libfuzzermsanopencv Platform Id: linux Crash Type: Use-of-uninitialized-value Crash Address: Crash State: cv::PAMDecoder::readHeader...