RFR: 8066444: Add CMS+ParNew support for promotion event

[Marcus Larsson]

Hi,

Please review the following patch to add PLAB tracing support for 
CMS+ParNew GC. The patch is a slightly modified version of the 
CMS+ParNew parts of Staffan Friberg's patch for JDK-8055845 [0]. With 
the modifications, the GCTracer no longer needs to be passed around as 
an argument, and can be fetched when the events are reported.

I tried refactoring the change to avoid the need for the other two added 
arguments as well, but since this code is part of a hot path I found no 
way of doing this without introducing a performance regression.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8066444/webrev.00/

Bug:
https://bugs.openjdk.java.net/browse/JDK-8066444

Testing:
local jtreg

Thanks,
Marcus

[0]: 
http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2014-December/011477.html