RFR: 8352218: RISC-V: Zvfh requires RVV [v3]

[Robbin Ehn]

> Hi please consider.
> 
> Added case to turn off UseZvfh when no RVV. 
> Which is the cause of the test issues, zvfh on but no rvv.
> 
> Also made all case identical and added no warning when default.
> Move them to the common init, as the "UseExtension" is not C2 specific.
> 
> Manual tested and some random compiler tests.
> 
> Thanks, Robbin

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - Merge branch 'master' into maxvector_0
 - Merge branch 'master' into maxvector_0
 - hwprobe deps
 - Merge branch 'master' into maxvector_0
 - Moved to common
 - Disable UseZvfh when no RVV

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24094/files
  - new: https://git.openjdk.org/jdk/pull/24094/files/2357c157..92908e1c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24094&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24094&range=01-02

  Stats: 6524 lines in 176 files changed: 2388 ins; 2313 del; 1823 mod
  Patch: https://git.openjdk.org/jdk/pull/24094.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24094/head:pull/24094

PR: https://git.openjdk.org/jdk/pull/24094