RFR: 8361602: [TESTBUG] serviceability/HeapDump/UnmountedVThreadNativeMethodAtTop.java deadlocks on exception [v3]

[Richard Reingruber]

> This pr moves the `notify()` call to the finally block to avoid the deadlock in `join()` if `verifyHeapDump(dumpFile)` throws an exception.
> 
> Testing was done with fastdebug and release builds on the main platforms and also on Linux/PPC64le and AIX.

Richard Reingruber has updated the pull request incrementally with one additional commit since the last revision:

  Wait while !done

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26213/files
  - new: https://git.openjdk.org/jdk/pull/26213/files/a4943345..13cb9ba3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26213&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26213&range=01-02

  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26213.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26213/head:pull/26213

PR: https://git.openjdk.org/jdk/pull/26213