RFR (trivial): 8241043: Expand assertions to identify thread with errant _stack_base

[Mikael Vidstedt]

Looks good.

Cheers,
Mikael

> On Mar 15, 2020, at 6:59 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> webrev: http://cr.openjdk.java.net/~dholmes/8241043/webrev/
> bug: https://bugs.openjdk.java.net/browse/JDK-8241043
> 
> This is a subtask of JDK-8239895 as I've been unable to reproduce the failures seen there. So this subtask augments a couple of assertions to try and assist with pinning down the actual bug.
> 
> I think this counts as trivial.
> 
> Testing: tiers 1-3
> 
> Thanks,
> David