RFR (XXS): 8010289: PSParallelCompact::marking_phase should use instance GCTracer

[Erik Helin]

Hi all,

the method PSParallelCompact::marking_phase takes a GCTracer* as 
argument. This is not needed since what is passed is just the address of 
the instance GCTracer, marking_phase can just use the instance GCTracer 
directly instead.

This change removes the argument and uses the instance GCTracer instead.

Webrev:
http://cr.openjdk.java.net/~ehelin/8010289/webrev.00/

Bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8010289

Thanks,
Erik