The unification of a bigger stack for the atmega platforms
makes some boards to not have enough memory to provide
the big stack plus the application code.
It is possible though, to override the stack size to a
smaller amount if running the test is necessary.
c3f7925c1c was the wrong fix for the described problem. The replying thread 2 needs a higher priority because otherwise the sender thread 1 may send before 2 is in receiving mode again.
