RFR: JDK-8305414: gtest/NMTGtests.java is failing various sub-tests [v3]

[Thomas Stuefe]

> [JDK-8304815](https://bugs.openjdk.org/browse/JDK-8304815) added the ability to use NMT for better hs-err reporting: we now ask NMT - if enabled - to make sense of otherwise unknown memory locations.
> 
> With C-heap blocks, the error printer now prints out a message if a memory location points into a live or dead malloc block. For details, see JDK-8304815 and the comments in mallocTracker.cpp.
> 
> The change came with its own gtest, which promptly started to fail intermittently. That failure was caused by a real issue the test found where we accidentally returned from MallocTracker::print_pointer_information() if we encountered unmapped memory (this makes the error intermittent). The return bypassed the block printing code, which made the test fail.
> 
> Patch fixes that, and also fixes some debug output in the test.
> 
> Tests: Ran the test manually on Linux aarch64; was able to reproduce the errors without patch, no errors with patch.

Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Revert problemlisting
 - Merge branch 'master' into JDK-8305414-gtest-NMTGtests.java-is-failing-various-sub-tests
 - Merge branch 'master' into JDK-8305414-gtest-NMTGtests.java-is-failing-various-sub-tests
 - JDK-8305414-gtest-NMTGtests.java-is-failing-various-sub-tests

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13296/files
  - new: https://git.openjdk.org/jdk/pull/13296/files/45065588..9afe9227

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13296&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13296&range=01-02

  Stats: 1961 lines in 18 files changed: 1480 ins; 354 del; 127 mod
  Patch: https://git.openjdk.org/jdk/pull/13296.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13296/head:pull/13296

PR: https://git.openjdk.org/jdk/pull/13296