RFR: 8276990: Memory leak in invoker.c fillInvokeRequest() during JDI operations

[Roman Kennke]

We observe a native memory leak when repeating JDI operations from Eclipse in a debuggee JVM. See bug report for details.

AFAICT, this happens because we override methodSignature of a possible pre-existing request object. I am not sure if there is a better place to deallocate the signature.

Also, I am not sure how to make an automated test for this. We (that is, the customer that reported the problem) verified that the memory leak disappears with the fix.

-------------

Commit messages:
 - 8276990: Memory leak in invoker.c fillInvokeRequest() during JDI operations

Changes: https://git.openjdk.java.net/jdk/pull/7306/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7306&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8276990
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7306.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7306/head:pull/7306

PR: https://git.openjdk.java.net/jdk/pull/7306