RFR: 8368897: RISC-V: Cleanup RV_EXT_FEATURE_FLAGS & RV_NON_EXT_FEATURE_FLAGS

[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 is not necessary, so we should be able to order flags in RV_EXT_FEATURE_FLAGS in any way we'd like to.

Thanks!

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Commit messages:
 - initial commit
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/27562/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27562&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368897
  Stats: 103 lines in 1 file changed: 44 ins; 48 del; 11 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