RFR: 8296401: ConcurrentHashTable::bulk_delete might miss to delete some objects [v2]

[Leo Korinth]

> ConcurrentHashTable::bulk_delete might miss to delete some objects if a bucket has more than 256 entries. Current uses of ConcurrentHashTable are not harmed by this behaviour. 
> 
> I modified gtest:ConcurrentHashTable to detect the problem (first commit), and fixed the problem in the code (second commit).
> 
> Tests passes tier1-3.

Leo Korinth has updated the pull request incrementally with two additional commits since the last revision:

 - growable stacked
 - Revert "working!"
   
   This reverts commit 5366f22c7202eaa2182976c084d02e9af4f56de0.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10983/files
  - new: https://git.openjdk.org/jdk/pull/10983/files/5366f22c..4508c0b8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10983&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10983&range=00-01

  Stats: 40 lines in 2 files changed: 7 ins; 4 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/10983.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10983/head:pull/10983

PR: https://git.openjdk.org/jdk/pull/10983