RFR: 8368897: RISC-V: Cleanup RV_EXT_FEATURE_FLAGS & RV_NON_EXT_FEATURE_FLAGS [v6]

[Hamlin Li]

> Hi,
> Can you help to review the patch?
> 
> This patch cleans up RV_EXT_FEATURE_FLAGS & RV_NON_EXT_FEATURE_FLAGS, as discussed https://github.com/openjdk/jdk/pull/27152#discussion_r2367109820:
> * reorder flags in alphabetic order for RV_EXT_FEATURE_FLAGS
> * move comments close to feature declaration for RV_EXT_FEATURE_FLAGS & RV_NON_EXT_FEATURE_FLAGS
> 
> We also discussed (https://github.com/openjdk/jdk/pull/27171#discussion_r2387195562) the assert introduced in https://github.com/openjdk/jdk/pull/24094, previously we think this will restrict the flags order in RV_EXT_FEATURE_FLAGS, but I found out that this  assert (<del>is not necessary</del>, so we should be able to order flags in RV_EXT_FEATURE_FLAGS in any way we'd like to) does not work as expected, will fix this in another pr.
> 
> Thanks!

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

  space

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27562/files
  - new: https://git.openjdk.org/jdk/pull/27562/files/f2cc974e..b995f7dd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27562&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27562&range=04-05

  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/27562.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27562/head:pull/27562

PR: https://git.openjdk.org/jdk/pull/27562