RFR: 8306823: Native memory leak in SharedRuntime::notify_jvmti_unmount/mount.

[Martin Doerr]

The code introduced by [JDK-8304303](https://bugs.openjdk.org/browse/JDK-8304303) uses `JNIHandles::make_local` which requires `JNIHandles::destroy_local` which is currently missing.

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Commit messages:
 - 8306823: Native memory leak in SharedRuntime::notify_jvmti_unmount/mount.

Changes: https://git.openjdk.org/jdk/pull/13641/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13641&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306823
  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13641.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13641/head:pull/13641

PR: https://git.openjdk.org/jdk/pull/13641