RFR: 8299817: [s390] AES-CTR mode intrinsic fails with multiple short update() calls [v2]

[Lutz Schmidt]

> This PR addresses an issue in the AES-CTR mode intrinsic on s390. When a message is ciphered in multiple, small (< 16 bytes) segments, the result is incorrect.
> 
> This is not just a band-aid fix. The issue was taken as a chance to restructure the code. though still complicated, It is now easier to read and (hopefully) understand.
> 
> Except for the new jetreg test, the changes are purely s390. There are no side effects on other platforms. Issue-specific tests pass. Other tests are in progress. I will update this PR once they are complete. 
> 
> **Reviews and comments are very much appreciated.**
> 
> @backwaterred could you please run some "official" s390 tests? Thanks.

Lutz Schmidt has updated the pull request incrementally with one additional commit since the last revision:

  8299817: Update copyright

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Changes:
  - all: https://git.openjdk.org/jdk/pull/11967/files
  - new: https://git.openjdk.org/jdk/pull/11967/files/7af2c3db..33722f27

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11967&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11967&range=00-01

  Stats: 29 lines in 5 files changed: 1 ins; 0 del; 28 mod
  Patch: https://git.openjdk.org/jdk/pull/11967.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11967/head:pull/11967

PR: https://git.openjdk.org/jdk/pull/11967