JDK-8151513: Remove debugging code from BarrierSet

[Bengt Rutisson]

Hi everyone,

Could I have a couple of reviews for this small change?

http://cr.openjdk.java.net/~brutisso/8151513/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8151513

There is some leftover debugging #if 0 code in barrierSet.cpp and 
barrierSet.inline.hpp.

Thanks,
Bengt