RFR: 8339317: Optimize ClassFile writeBuffer

[Shaojin Wen]

A small optimization, optimize the BufferWriter implementation and use of ClassFile, provide faster patchInt and skip

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Commit messages:
 - Suggestions from @cl4es
 - fix build error
 - remove BufWriter#patchInt
 - optimize BufWriterImpl#patchInt

Changes: https://git.openjdk.org/jdk/pull/20780/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20780&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339317
  Stats: 48 lines in 8 files changed: 28 ins; 0 del; 20 mod
  Patch: https://git.openjdk.org/jdk/pull/20780.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20780/head:pull/20780

PR: https://git.openjdk.org/jdk/pull/20780