RFR: 8324681: Replace NULL with nullptr in HotSpot jtreg test native code files [v3]

[Coleen Phillimore]

> This mechanically replaces NULL with nullptr in hpp/cpp native files in test native code.  This didn't attempt to change NULL in comments or strings to just null.  If you run into this and it bothers you after this push, you can change it in a smaller patch. I didn't see any when it was scrolling by to make my script more complicated.
> 
> Ran tier1-4 testing.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Fix nullptr only contained in strings.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17593/files
  - new: https://git.openjdk.org/jdk/pull/17593/files/e15a3a0b..33786c7d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17593&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17593&range=01-02

  Stats: 19 lines in 3 files changed: 0 ins; 0 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/17593.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17593/head:pull/17593

PR: https://git.openjdk.org/jdk/pull/17593