6916623: Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

Added new product ObjectAlignmentInBytes flag to control object alignment.

Reviewed-by: twisti, ysr, iveresov

hotspot/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp

@@ -1414,6 +1414,8 @@ PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
 {
   assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
          "must move left or to a different space");
+  assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
+         "checking alignment");
 }
 #endif // ASSERT