RFR: 8339317: Optimize ClassFile writeBuffer [v7]

[Shaojin Wen]

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

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 13 commits:

 - Merge remote-tracking branch 'origin/class_file_buf_writer_imp_202408_patch_int' into class_file_buf_writer_imp_202408_patch_int
 - Eliminate redundant variables
 - buf skip
 - Merge remote-tracking branch 'upstream/master' into class_file_buf_writer_imp_202408_patch_int
   
   # Conflicts:
   #	src/java.base/share/classes/jdk/internal/classfile/impl/AbstractPoolEntry.java
 - Merge remote-tracking branch 'upstream/master' into class_file_buf_writer_imp_202408_patch_int
 - Merge remote-tracking branch 'upstream/master' into class_file_buf_writer_imp_202408_patch_int
 - revert skip
 - Update src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java
   
   Co-authored-by: Claes Redestad <claes.redestad at oracle.com>
 - Update src/java.base/share/classes/jdk/internal/classfile/impl/Util.java
   
   Co-authored-by: Claes Redestad <claes.redestad at oracle.com>
 - Suggestions from @cl4es
 - ... and 3 more: https://git.openjdk.org/jdk/compare/8fb8cd85...e7f57a6f

-------------

Changes: https://git.openjdk.org/jdk/pull/20780/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20780&range=06
  Stats: 56 lines in 7 files changed: 32 ins; 4 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