RFR [jdk11]: 8234691: Potential double-free in ParallelSPCleanupTask constructor

[Baesken, Matthias]

Hello, please review the backport of 8234691 to jdk11 .
The patch needed a bit of adjustment, especially  I had to add the
  #define NONCOPYABLE(C)
that is used in workgroup.hpp but was not present in jdk11      src/hotspot/share/utilities/globalDefinitions.hpp  .


Bug/webrev :

https://bugs.openjdk.java.net/browse/JDK-8234691

http://cr.openjdk.java.net/~mbaesken/webrevs/8234691_0_jdk11/

Original jdk/jdk webrev :

https://hg.openjdk.java.net/jdk/jdk/rev/3773a32c1ef8

Thanks, Matthias