[jdk11u-dev] RFR: 8287596: Reorg jdk.test.lib.util.ForceGC

[Alexey Bakhtin]

Hello
I'd like to backport this enhancement to fix regression in java/awt/List/ListGarbageCollectionTest/AwtListGarbageCollectionTest.java caused by JDK-8300727. The backport of JDK-8300727 requires JDK-8287596 to be applied first.

The main differences from the JDK17 patch are the following:
- Reference::refersTo() is introduced in JDK16. Reference::get is used instead
- test/jdk/java/lang/ClassLoader/nativeLibrary/NativeLibraryTest.java in JDK11 does not use ForceGC. Skipped
- no test/jdk/java/lang/invoke/defineHiddenClass/UnloadingTest.java in JDK11
- This patch also includes JDK-8261851 changes as part of the test/jdk/java/lang/reflect/callerCache/ReflectionCallerCacheTest.java patch

All related jtreg tests passed.

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Commit messages:
 - Backport 82a8bd7e92a1867b0c82f051361938be8610428d

Changes: https://git.openjdk.org/jdk11u-dev/pull/2640/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2640&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287596
  Stats: 105 lines in 4 files changed: 18 ins; 62 del; 25 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2640.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2640/head:pull/2640

PR: https://git.openjdk.org/jdk11u-dev/pull/2640