RFR: 8364280: NMTCommittedVirtualMemoryTracker.test_committed_virtualmemory_region_vm fails with assertion "negative distance"

[Afshin Zafari]

The VirtualMemoryTracker API uses a tree internally for tracking the memory regions and their states/info. This tree should not be changed when looking for some regions. If not synch'ed, the nodes in the tree may change meanwhile and the retrieved info are not as expected. The unit test in this PR did not synch these looking up with VMT. The corresponding lock is used to address the problem.

Tests:
local: linux-x64-debug NMTGtests
mach5: tiers 1-5, {macosx-aarch64, linux-x64, windows-x64} x {debug, release}

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Commit messages:
 - 8364280: NMTCommittedVirtualMemoryTracker.test_committed_virtualmemory_region_vm fails with assertion "negative distance"

Changes: https://git.openjdk.org/jdk/pull/26689/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26689&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364280
  Stats: 21 lines in 1 file changed: 8 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/26689.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26689/head:pull/26689

PR: https://git.openjdk.org/jdk/pull/26689