review (XS) for 6679708

[Tom Rodriguez]

6679708: No_Safepoint_Verifier and BacktraceBuilder have uninitialized 
fields
Summary: fix or remove uninitialized fields
Reviewed-by:

While doing some testing with valgrind I tripped across a couple
uninitialized fields.  BacktraceBuilder has an extra field which is
uninitialized and is benignly useless.  No_Safepoint_Verifier doesn't
properly initialize the _activated field.  Normally it should be true
and garbage on the stack is more likely to be non-zero so mostly I
think this doesn't matter either.  The fix is simply remove the extra
field from BacktraceBuilder and initialize the field in
No_Safepoint_Verifier.

http://webrev.invokedynamic.info/never/6679708