qpdf/qpdf_fuzzer: Use-of-uninitialized-value in deflate_slow

Detailed report: https://oss-fuzz.com/testcase?key=5710136049401856 Project: qpdf Fuzzer: libFuzzerqpdffuzzer Fuzz target binary: qpdffuzzer Job Type: libfuzzermsanqpdf Platform Id: linux Crash Type: Use-of-uninitialized-value Crash Address: Crash State: deflateslow deflate PlFlate::handleData...