RFR(S): jdk11u-dev backport 8181143: Introduce diagnostic flag to abort VM on too long VM operations

[Doerr, Martin]

Hi,

I'd like to backport this change to jdk11u because it's a helpful feature to diagnose too long running VM operations.

bug:
https://bugs.openjdk.java.net/browse/JDK-8181143

original change:
http://hg.openjdk.java.net/jdk/jdk/rev/c403f39ec349

jdk11u webrev:
http://cr.openjdk.java.net/~mdoerr/8181143_AbortVMOnVMOperationTimeout/jdk11u/webrev.00/

I only had to insert the #include "runtime/task.hpp" manually into vmThread.hpp because the succeeding include was changed in jdk12.

Note that this change needs to get backported together with JDK-8215374 which is a simply fix for the original change which applies cleanly.

Please review.

Best regards,
Martin