RFR (M): 8029396: PPC64 (part 212): Several memory ordering fixes in C-code.

[Lindenmaier, Goetz]

Hi,

This change contains a row of fixes to the memory ordering in runtime, GC etc.
http://cr.openjdk.java.net/~goetz/webrevs/8029396-0-memo/

These are:
- Accessing arrays in CMS (compactibleFreeListSpace.cpp)
- CMS: Do release when marking a card dirty. The release must only be done if GC is running. (several files)
- Method counter initialization (method.hpp).
- Order accessing f1/f2 in constant pool cache.
- Release stores in OopMapCache constructor (instanceKLass.cpp).
- BiasedLocking: Release setting object header to displaced mark.
- Release state of nmethod sweeper (sweeper.cpp).
- Do barriers when writing the thread state (thread.hpp).

Please review and test this change.

If requested, I can part this into smaller changes.  But for now
I wanted to put them all into one change as they all address the
problems with the PPC memory model.

Best regards,
  Goetz.