RFR: 8301136: Improve unlink() and unlink_all() of ResourceHashtableBase [v4]

[Xin Liu]

> 1. Apply the same idea of JDK-8300184 to unlink().
> 2. Because ResourceHashtableBase doesn't support copy assignment, client of it has to purge all elements first when it needs to assign it. We would like provide a specialized version called 'unlink_all()'.  We don't need to update each node's _next in this case. We only nullify all buckets. 
> 3. This patch also provides a specialized version of unlink_all() for destructor. We don't even update buckets. it's dead anyway.

Xin Liu has updated the pull request incrementally with one additional commit since the last revision:

  Use unlink_all() in JvmtiTagMapTable::clear.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12213/files
  - new: https://git.openjdk.org/jdk/pull/12213/files/2fa173c4..0e003bab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12213&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12213&range=02-03

  Stats: 13 lines in 2 files changed: 0 ins; 11 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12213.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12213/head:pull/12213

PR: https://git.openjdk.org/jdk/pull/12213