[jdk15u-dev] RFR: 8258077: Using -Xcheck:jni can lead to a double-free after JDK-8193234

[Yuri Nesterenko]

I'd like to backport this useful fix to 15u, too. tier-tested on several platforms.

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Commit messages:
 - Backport 712014c5956cf74982531d212b03460843e4e5b6

Changes: https://git.openjdk.java.net/jdk15u-dev/pull/206/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk15u-dev&pr=206&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258077
  Stats: 322 lines in 5 files changed: 303 ins; 6 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk15u-dev/pull/206.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk15u-dev pull/206/head:pull/206

PR: https://git.openjdk.java.net/jdk15u-dev/pull/206