RFR: 8065227: Report allocation context stats at end of cleanup

[Stefan Johansson]

Hi,

Please review this forward port to fix this issue in jdk9:
https://bugs.openjdk.java.net/browse/JDK-8065227

Webrev:
jdk9: http://cr.openjdk.java.net/~sjohanss/8065227/jdk9-hotspot.00/
jdk8u40: http://cr.openjdk.java.net/~sjohanss/8065227/hotspot.00/

Old review thread:
http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2014-November/011348.html

Summary:
The changeset didn't apply clean due to surrounding changes in 
concurrentMark.cpp, but the idea for the fix remains the same. Move the 
allocation_context_stats-update to the clean up phase instead of remark.

Testing:
* Built through JPRT

Thanks,
Stefan