RFR: 8327173: HotSpot Style Guide needs update regarding nullptr vs NULL [v3]

[Kim Barrett]

> Please review this change to update the HotSpot Style Guide's discussion of
> nullptr and its use.
> 
> I suggest this is an editorial rather than substantive change to the style
> guide.  As such, the normal HotSpot PR process can be used for this change.

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into nullptr-style
 - respond to shipilev comments
 - update nullptr usage

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18101/files
  - new: https://git.openjdk.org/jdk/pull/18101/files/13dc01ac..461bf280

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18101&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18101&range=01-02

  Stats: 72989 lines in 714 files changed: 2663 ins; 68821 del; 1505 mod
  Patch: https://git.openjdk.org/jdk/pull/18101.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18101/head:pull/18101

PR: https://git.openjdk.org/jdk/pull/18101