int overflow during serialization of a FULL type HLL when log2m and regwidth are both large

[blinsay]

Originally reported by @hossman aggregateknowledge/java-hll#17

Potential fix contributed by @ragstorooks aggregateknowledge/java-hll#18

---

BigEndianAscendingWordSerializer and BigEndianAscendingWordDeserializer both suffer from int overflow bugs: multiplying large ints and then assigning to long instead of casting those ints to longs before multiplying them.

I don't have a pull request handy (since this project no longer seems actively maintained, we've forked & imported directly into the Apache Solr code base) but I wanted to file this issue to make existing users aware of the bug -- you can see the details involved in fixing/testing in this issue/commit in the Lucene/Solr code base...

https://svn.apache.org/viewvc?view=revision&revision=1697969
https://issues.apache.org/jira/browse/SOLR-7954