RFR: 8327652: S390x: Implements SLP support [v12]

[Sidraya Jayagond]

> This PR Adds SIMD support on s390x.

Sidraya Jayagond has updated the pull request incrementally with one additional commit since the last revision:

  Disable vector instructions from string intrinsics
  
  Address Lutz's comments.
  Disable vector instructions from string intrinsics will be
  enabled once PR to JDK-8336356 gets integrates.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18162/files
  - new: https://git.openjdk.org/jdk/pull/18162/files/34341aed..8a96bf73

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18162&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18162&range=10-11

  Stats: 52 lines in 4 files changed: 21 ins; 22 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/18162.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18162/head:pull/18162

PR: https://git.openjdk.org/jdk/pull/18162