6994628: G1: Test gc/gctests/FinalizeTest05 fails (one live object is finalized)
Summary: The Solaris Studio 12 update 1 C++ compiler was incorrectly re-ordering the reads of an object's mark word in oopDesc::forward_to_atomic(). This opened a small window where one thread could execute the successful CAS path even though another thread had already successfully forwarded the object. This could result in an object being copied twice. The code in oopDesc::forward_to_atomic() was changed to read the mark word once.
Reviewed-by: ysr, tonyp