XRef::removeIndirectObject: Fix overflow of gen
Also make the check in XRef::addIndirectObject that looks for a free and usable entry a bit more robust (!= to <) than 65535
oss-fuzz/28032
Also make the check in XRef::addIndirectObject that looks for a free and usable entry a bit more robust (!= to <) than 65535
oss-fuzz/28032