[aarch64-port-dev ] Redundant guard conditions caused guarantee failure

[Roman Kennke]

Hi there,

> Someone would like to have a look at this? It's probably a bug and may have impact on applications.

I am looking into it.

Your proposed fix looks correct.

However, we do have a number of deviations in our version of that code
(synchronizer.cpp, thread.cpp), compared to vanilla jdk8u code. I'm
looking into reverting all of it to upstream version, in order to
minimize the risk of such breakages.

Thanks,
Roman