Abort the console thread when heap is low.

Abort the console thread when heap is low.

Previously, a random running thread was aborted, e.g. the
single-threaded workload.  Recently, just the notification subscribers
were aborted.  But it is common for there to be NO subscribers,
e.g. during a single-threaded workload (our own build!).  Now the
console thread is also aborted (and notifications are punted).