RFR: 8324679: Replace NULL with nullptr in HotSpot .ad files [v2]

[Coleen Phillimore]

> This is a straightforward mechanical (sed) replacement of NULL with nullptr.  One string was adjusted to not say nullptr ptr.  nullptr makes sense in the comments so I didn't change them.
> 
> Tested with tier1 Oracle platforms and build test with linux-x64-zero,linux-x64-zero-debug,linux-s390x-open,linux-arm32-debug,linux-ppc64le-debug,linux-riscv64-debug

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

  Fix comments to Null Pointer and strings to null pointer.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17658/files
  - new: https://git.openjdk.org/jdk/pull/17658/files/7475cfe8..019b6027

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17658&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17658&range=00-01

  Stats: 23 lines in 8 files changed: 0 ins; 0 del; 23 mod
  Patch: https://git.openjdk.org/jdk/pull/17658.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17658/head:pull/17658

PR: https://git.openjdk.org/jdk/pull/17658