RFR: 8352248: Check if CMoveX is supported

[Hamlin Li]

Hi,
Can you help to review this patch?

Currenlty, seems CMoveX are fully supported on most platforms, except of riscv64.
On riscv64, there is no efficient way to implement CMoveF/D as other CMoveX (e.g. CMoveI), but it will still bring benefit by just supporting CMoveX without CMoveF/D. This patch is to supply such option.

As other platforms already supported CMoveX, this patch should not impact them, as `!CMoveNode::supported(_igvn.type(phi))` should always be false.

BTW, in a subsequent pr for riscv, I'll implement CMoveX except of CMoveF/D, and also return false for CMoveF/D in Matcher::match_rule_supported.

Thanks!

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/24095/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24095&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352248
  Stats: 17 lines in 3 files changed: 16 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24095.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24095/head:pull/24095

PR: https://git.openjdk.org/jdk/pull/24095