RFR: 8253821: Improve ByteBuffer performance with GCM [v5]

[Anthony Scarpino]

On Thu, 12 Nov 2020 16:34:29 GMT, Anthony Scarpino <ascarpino at openjdk.org> wrote:

>> This is an update for all of Valerie's comments and adding a test to verify different buffer types and configurations
>
> The latest update should address all outstanding comments.  The biggest change was to the test, which had major reorganization and created tests that increments data sizes for update and doFinal ops byte-by-byte to check for any errors.  That should reduce concerns about buffer corruption.

The biggest part of this change is the addition of overlap protection and the tests to verify it for GCM, as there were none in the open repo.  Additionally, GCMBufferTest had some significant changes to clean it up and handle offsets better.  All tests pass.  With RDP1 coming, I want to get this into the repo soon, so please limit comments to bugs. Any "nice to have" changes, they can be added onto follow-on changes I plan.

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PR: https://git.openjdk.java.net/jdk/pull/411