RFR: 8314243: Make VM_Exit::wait_for_threads_in_native_to_block wait for user threads time configurable

[Jiangli Zhou]

CSR: https://bugs.openjdk.org/browse/JDK-8314305

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Commit messages:
 - Merge branch 'master' into JDK-8314243
 - 8314243: Make VM_Exit::wait_for_threads_in_native_to_block wait for user threads time configurable

Changes: https://git.openjdk.org/jdk/pull/16591/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16591&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314243
  Stats: 13 lines in 2 files changed: 6 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/16591.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16591/head:pull/16591

PR: https://git.openjdk.org/jdk/pull/16591