RFR: 8346717: serviceability/dcmd/vm/SystemDumpMapTest.java failing on Windows with "Stack base not yet set for thread id"

[Simon Tooke]

This test fixes an issue with incomplete Windows threads not yet having a stack.  A test for a null stack_base is added to guard against the potential null dereference.  An additional test using ZGC is added to the jtreg SystemMapTest.

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

Commit messages:
 - Merge branch 'pr_8346717' of https://github.com/stooke/jdk into pr_8346717
 - restore deleted function name
 - add ZGC run of SystemMapTest
 - fix test for unready thread on Windows

Changes: https://git.openjdk.org/jdk/pull/22870/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22870&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346717
  Stats: 13 lines in 2 files changed: 12 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22870.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22870/head:pull/22870

PR: https://git.openjdk.org/jdk/pull/22870