[vectorIntrinsics+compress] RFR: 8274889: Intrinsify Vector.expand/compress APIs for X86 [v5]

[Jatin Bhateja]

> - Common C2 compiler entry point for compress/expand APIs.
> - Inline expansion handling and C2 graph creation.
> - For X86 current backed support is added for AVX512 which offers direct compress/expand instructions.

Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:

  8274889: Review comments resolution.

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Changes:
  - all: https://git.openjdk.java.net/panama-vector/pull/146/files
  - new: https://git.openjdk.java.net/panama-vector/pull/146/files/c899a604..26cf1652

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=146&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=146&range=03-04

  Stats: 252 lines in 41 files changed: 42 ins; 186 del; 24 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/146.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/146/head:pull/146

PR: https://git.openjdk.java.net/panama-vector/pull/146