RFR(S): JDK-8047330: Remove unrolled card loops in G1 SparsePRTEntry

[Andreas Sjöberg]

Hi all,

can I please have reviews for this patch that removes the unrolled 
for-loops in sparsePRT.cpp.

I ran some performance benchmarks and could not see any benefits in 
keeping the unrolled for loops. SPECjbb2013 shows a 3.48% increase on 
Linux x64 actually.

Webrev: http://cr.openjdk.java.net/~jwilhelm/8047330/webrev/

Testing: jprt, specjbb2005, specjvm2008, specjbb2013

Thanks,
Andreas