RFR: 8371820: Further AES performance improvements for key schedule generation [v2]

[Martin Doerr]

> This fix simplifies the hotspot intrinsics for some platforms and optimizes the key computation for encryption. We can save the `genInvRoundKeys` computation when we only do encryption.
> 
> The micro:org.openjdk.bench.javax.crypto.AESReinit benchmark results are improved by 17% for ppc64 and 26% for x86_64.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Improve comment and minor cleanup.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28299/files
  - new: https://git.openjdk.org/jdk/pull/28299/files/477a3dda..b03e6b43

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28299&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28299&range=00-01

  Stats: 8 lines in 2 files changed: 2 ins; 1 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/28299.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28299/head:pull/28299

PR: https://git.openjdk.org/jdk/pull/28299