RFR: 8339290: Optimize ClassFile Utf8EntryImpl#writeTo [v2]

[Shaojin Wen]

> Use fast path for ascii characters 1 to 127 to improve the performance of writing Utf8Entry to BufferWriter.

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  add comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20772/files
  - new: https://git.openjdk.org/jdk/pull/20772/files/5a7b334a..28bd454c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20772&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20772&range=00-01

  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/20772.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20772/head:pull/20772

PR: https://git.openjdk.org/jdk/pull/20772