RFR: 8339290: Optimize ClassFile Utf8EntryImpl#writeTo [v16]

[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 two additional commits since the last revision:

 - suggestion from @cl4es
 - Revert "countGreaterThanZero -> CountNonNegatives"
   
   This reverts commit 431f55b46daf86fe9f2e24a2587eba8f65d847ff.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20772/files
  - new: https://git.openjdk.org/jdk/pull/20772/files/431f55b4..c0e425cd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20772&range=15
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20772&range=14-15

  Stats: 160 lines in 6 files changed: 72 ins; 72 del; 16 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