RFR: 8327652: S390x: Implements SLP support [v4]

[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:

  Use Op_VecX instead of Op_RegF
  
  Signed-off-by: Sidraya <sidraya.jayagond at ibm.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18162/files
  - new: https://git.openjdk.org/jdk/pull/18162/files/487c57db..3caa470c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18162&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18162&range=02-03

  Stats: 265 lines in 8 files changed: 1 ins; 155 del; 109 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