RFR: 8334397: RISC-V: verify perf of ReverseBytesS/US

[Hamlin Li]

Hi,
Can you help to review this patch?
Thanks!

This is similar with previous JDK-8334396.
Added some tests.

### Test
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  | Tests | Scores | Errors | Unit
-- | -- | -- | -- | --
Intrinsic, +zbb, +rvv | Characters.reverseBytes | 1654.535 | 69.36 | ns/op
  | Shorts.reverseBytes | 1795.403 | 44.015 | ns/op
Intrinsic, +zbb, -rvv | Characters.reverseBytes | 1649.752 | 74.965 | ns/op
  | Shorts.reverseBytes | 1798.637 | 49.52 | ns/op
Intrinsic, -zbb, +rvv | Characters.reverseBytes | 2279.588 | 44.222 | ns/op
  | Shorts.reverseBytes | 2441.674 | 63.895 | ns/op
Intrinsic, -zbb, -rvv | Characters.reverseBytes | 2288.876 | 49.099 | ns/op
  | Shorts.reverseBytes | 2454.454 | 94.004 | ns/op
No intrinsic | Characters.reverseBytes | 1629.722 | 23.656 | ns/op
  | Shorts.reverseBytes | 2108.81 | 43.378 | ns/op

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/19830/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19830&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8334397
  Stats: 129 lines in 4 files changed: 98 ins; 31 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19830.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19830/head:pull/19830

PR: https://git.openjdk.org/jdk/pull/19830