RFR (S): JDK-8014339: Improve assert and remove some dead code from parMarkBitMap.hpp/cpp

[Bengt Rutisson]

Hi all,

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

http://cr.openjdk.java.net/~brutisso/8014339/webrev.00/

Background:

To be able to analyze crashes due to JDK-8011596 better we need to get 
more information from an assert in ParMarkBitMap::verify_addr(). While 
looking at the code in parMarkBitMap.cpp/hpp I realized that there is 
some dead code to clean up there. This fix adds the extra information to 
the assert and cleans up the dead code.

Thanks,
Bengt