[jdk21u-dev] RFR: 8347840: Fix testlibrary compilation warnings

[Goetz Lindenmaier]

I would like to backport this to keep the test suite up to date. 

make/test/BuildTestLib.gmk
I had to resolve, the code and listed warnings differ considerably.
Nevertheless obvious resolve.

test/lib/jdk/test/lib/apps/LingeredApp.java
test/lib/jdk/test/lib/classloader/ClassUnloadCommon.java
test/lib/jdk/test/lib/hprof/model/JavaHeapObject.java
test/lib/jdk/test/lib/hprof/model/Root.java
test/lib/jdk/test/lib/hprof/model/Snapshot.java
test/lib/jdk/test/lib/jfr/Events.java
test/lib/jdk/test/lib/net/IPSupport.java
test/lib/jdk/test/lib/thread/VThreadPinner.java
test/lib/jdk/test/lib/thread/VThreadRunner.java
Resolved Copyright.

test/lib/jdk/test/lib/os/linux/HugePageConfiguration.java
This file was moved by "8340422: ZGC: TestAllocateHeapAt.java should not run with transparent hugepages".
The patch to the code applies clean after adapting the path, only the Copyright requires resolving.

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Commit messages:
 - Backport 2ca1b4d48da7eb9b5baf0ac213f3ce87f47dd316

Changes: https://git.openjdk.org/jdk21u-dev/pull/1830/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1830&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347840
  Stats: 120 lines in 30 files changed: 25 ins; 42 del; 53 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1830.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1830/head:pull/1830

PR: https://git.openjdk.org/jdk21u-dev/pull/1830