RFR: 8319439: Move BufferNode from PtrQueue files to new files [v2]

[Kim Barrett]

> Please review this simple (trivial?) change that moves the BufferNode class
> from share/gc/shared/ptrQueue.[ch]pp to new files
> share/gc/shared/bufferNode.[ch]pp.  The code (as opposed to the surrounding
> boiler plate and #include's) was moved unchanged.
> 
> This led to adding #include's of the new header file to a bunch of other files
> (include what you use), in some cases eliminating the need to #include
> ptrQueue.hpp.  Also tidied up the #include's for ptrQueue.[ch]pp to take
> advantage of the split.
> 
> Also, the gtest gc/shared/test_ptrQueueBufferAllocator.cpp is renamed to  
> gc/shared/test_bufferNodeAllocator.cpp, with some adjustments to includes and
> test naming.
> 
> Testing:
> mach5 tier1

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Merge branch 'master' into buffer-node
 - fixup gtest after rename
 - move test
 - move BufferNode to new files

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

Changes: https://git.openjdk.org/jdk/pull/16506/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16506&range=01
  Stats: 383 lines in 17 files changed: 223 ins; 152 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/16506.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16506/head:pull/16506

PR: https://git.openjdk.org/jdk/pull/16506