RFR: 8339475: Check return value of pthread_create in jdk coding [v3]

[Matthias Baesken]

> It has been discussed that checking the return value of pthread_create should be done.
> See the discussion here https://github.com/openjdk/jdk/pull/20812 about the splashscreen coding .

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  some macOS cleanup

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21182/files
  - new: https://git.openjdk.org/jdk/pull/21182/files/c04a074b..8fd42bb2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21182&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21182&range=01-02

  Stats: 14 lines in 2 files changed: 3 ins; 6 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/21182.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21182/head:pull/21182

PR: https://git.openjdk.org/jdk/pull/21182