RFR(XS): 8044090: C1: Old value instead of new one is passed to post-barrier in UnsafeGetAndSetObject

[Igor Veresov]

I didn’t notice this before but in UnsafeGetAndSetObject on C1 SPARC we’re passing an old value (which we are getting as a result of the xchg) to the post-barrier, while it really expect the new value (what was stored into memory).

Webrev: http://cr.openjdk.java.net/~iveresov/8044090/webrev.00/

Thanks!
igor