RFR: 8327058: RISC-V: make Zcb experimental [v2]

[Hamlin Li]

> Hi,
> Can you review the patch to add a flag for Zcb extension to enable user to control it?
> Thanks.
> 
> As discussed in [1], it's good to give a flag to control Zcb, and currently it's good to make it experimental.
> 
> [1] https://github.com/openjdk/jdk/pull/17698#discussion_r1505364098

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  group experimental flags

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18070/files
  - new: https://git.openjdk.org/jdk/pull/18070/files/500a6ea2..81acfdb3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18070&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18070&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18070.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18070/head:pull/18070

PR: https://git.openjdk.org/jdk/pull/18070