RFR: 8316641: VarHandle template classes can share code in the base class [v3]

[Chen Liang]

> VarHandle implementations have many static fields and methods that can be pulled to the common superclass to avoid repeated initialization and code duplication.
> 
> In addition, the Unsafe-based Buffer field access are replaced by usage of public methods or JavaNioAccess.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 163 commits:

 - Post-merge cleanup
 - Merge branch 'pr/15103' of https://github.com/openjdk/jdk into cleanup/vh-template-share
 - byte array var handles can share a common base class
 - Clean up VarHandle template classes
 - 8316229: Enhance class initialization logging
   
   Reviewed-by: shade, coleenp
 - 8316627: JViewport Test headless failure
   
   Reviewed-by: dcubed, prr
 - 8316156: ByteArrayInputStream.transferTo causes MaxDirectMemorySize overflow
   
   Reviewed-by: alanb
 - 8316532: Native library copying in BuildMicrobenchmark.gmk cause dups on macOS
   
   Reviewed-by: ihse, redestad
 - 8315869: UseHeavyMonitors not used
   
   Reviewed-by: dcubed, alanb
 - 8316562: serviceability/sa/jmap-hprof/JMapHProfLargeHeapTest.java times out after JDK-8314829
   
   Reviewed-by: dholmes, kevinw, dcubed
 - ... and 153 more: https://git.openjdk.org/jdk/compare/1f3248df...f291cabb

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

Changes: https://git.openjdk.org/jdk/pull/15854/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15854&range=02
  Stats: 68704 lines in 1907 files changed: 21583 ins; 14286 del; 32835 mod
  Patch: https://git.openjdk.org/jdk/pull/15854.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15854/head:pull/15854

PR: https://git.openjdk.org/jdk/pull/15854