RFR: 8325621: Improve jspawnhelper version checks [v4]

[Chad Rakoczy]

> Fix for [8325621](https://bugs.openjdk.org/browse/JDK-8325621)
> 
> Updates jspawnhelper to check that JDK version and jspawnhelper version are the same. Updates test to include check for version. Also tested manually by replacing jspawnhelper with incorrect version to confirm that check works.

Chad Rakoczy has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 10 commits:

 - Merge branch 'master' into JDK-8325621-2
 - Update style and improve error messages
 - Print to stdout instead of stderr
 - Compare version using VERSION_STRING
 - Code cleanup
 - Remove string.h include
 - Update test
 - Pass version as integer instead of string
 - Read in version using int instead of string
 - 8325621: Improve jspawnhelper version checks

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Changes: https://git.openjdk.org/jdk/pull/18204/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18204&range=03
  Stats: 59 lines in 5 files changed: 47 ins; 4 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/18204.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18204/head:pull/18204

PR: https://git.openjdk.org/jdk/pull/18204