RFR: 8308118: Avoid multiarray allocations in AESCrypt.makeSessionKey [v2]

[Aleksey Shipilev]

> One of our services has a hot path with AES/GCM cipher reuse. The JDK code reinitializes the session key on that path, and [JDK-8308105](https://bugs.openjdk.org/browse/JDK-8308105) shows up prominently there. While [JDK-8308105](https://bugs.openjdk.org/browse/JDK-8308105) is being fixed, it would take significantly more work: there are multiple issues of differing complexity, impact, and risk. 
> 
> Meanwhile, we can work this issue around by avoiding the multiarray allocations in AESCrypt.makeSessionKey. We can go even deeper: replace the multi-array with the flat array and drop `expandToSubKey` completely.
> 
> 
> Example profile is in the bug.
> 
> On new benchmark and M1 Mac:
> 
> 
> Benchmark       Mode  Cnt    Score   Error  Units
> 
> # Before
> AESReinit.test  avgt   15  873,842 ± 6,911  ns/op
> 
> # After
> AESReinit.test  avgt   15  347,632 ± 8,764  ns/op
> 
> 
> Additional testing:
>  - [x] Benchmarks
>  - [ ] macos-aarch64-server-release, `jdk_security`
>  - [ ] linux-x86_64-server-fastdebug, `tier1 tier2`
>  - [ ] linux-aarch64-server-fastdebug, `tier1 tier2`

Aleksey Shipilev has updated the pull request incrementally with three additional commits since the last revision:

 - Micro-optimizations
 - Handle Kd
 - Handle Ke

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13996/files
  - new: https://git.openjdk.org/jdk/pull/13996/files/7842e0e2..bb712183

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13996&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13996&range=00-01

  Stats: 72 lines in 1 file changed: 9 ins; 43 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/13996.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13996/head:pull/13996

PR: https://git.openjdk.org/jdk/pull/13996