libreoffice/hwpfuzzer: Bad-cast to HMemIODev from invalid vptr in SkipPrivateBlock

Project: git://anongit.freedesktop.org/libreoffice/core Detailed report: https://oss-fuzz.com/testcase?key=5748792192663552 Project: libreoffice Fuzzer: libFuzzerlibreofficehwpfuzzer Fuzz target binary: hwpfuzzer Job Type: libfuzzerubsanlibreoffice Platform Id: linux Crash Type: Bad-cast Crash...