RFR: 8254884: Make sure jvm does not crash with Arm SVE and Vector API [v2]

[Ningsheng Jian]

> Currently we have not implemented all Arm SVE code generation for Vector API specific nodes. To make sure hotspot does
> not crash with bad AD file (as NEON has implemented them), we simply add those OPs to unsupported op list.
> This is the port and minor cleanup of JDK-8253211 in repo-panama: https://github.com/openjdk/panama-vector/pull/7 with
> Op_VectorUnbox (not for codegen) and Op_VectorMaskWrapper (actually unused node. dead code?) removed from the
> unsupported op list and Op_VectorLoadConst added.  Test: tier1-3 on AArch64 and x86_64 as well as Vector API tests on
> AArch64 SVE.

Ningsheng Jian has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments from Vladimir.
  
  Change-Id: Ia484dc59f41d265972f1253193d1d7d7cb032a12

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/726/files
  - new: https://git.openjdk.java.net/jdk/pull/726/files/1e51f419..9bfa188c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=726&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=726&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/726.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/726/head:pull/726

PR: https://git.openjdk.java.net/jdk/pull/726