PDP10, PDP11: Fix compiler indicated invalid check.  Fixed #118
PDP11, PDP10, AltairZ80: Fixed cases where assert() macro is called with an expression which has side effects and therefore wouldn't get executed if compiled with NDEBUG defined.
PDP11, PDP10, VAX, AltairZ80: enhanced the macro which aborts on an unexpected status from an expression with side effects to also write a message to sim_log or sim_deb if they happen to be open.