RFR: JDK-8300240: Replace NULL with nullptr in share/ci/ [v2]

[Johan Sjölen]

> Do the conversion in the share/ci/ sub-directory and all of its files.

Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:

  Fix issues found by vnkozlov

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12029/files
  - new: https://git.openjdk.org/jdk/pull/12029/files/248c8faf..acb9f5e6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12029&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12029&range=00-01

  Stats: 5 lines in 4 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/12029.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12029/head:pull/12029

PR: https://git.openjdk.org/jdk/pull/12029