Interpreter_Integer: Correct precedence of overflow check in nego

The overflow check needs to occur before the condition register update
due to the fact that the summary overflow (SO) bit is used in the
updating of the condition register. If we set any overflow bits after
updating the CR, then we can potentially incorrectly report that an
overflow did not happen (in the case the SO bit wasn't set previously).

Source/Core/Core/PowerPC/Interpreter/Interpreter_Integer.cpp

@@ -591,11 +591,11 @@ void Interpreter::negx(UGeckoInstruction inst)
 
   rGPR[inst.RD] = (~a) + 1;
 
-  if (inst.Rc)
-    Helper_UpdateCR0(rGPR[inst.RD]);
-
   if (inst.OE)
     PowerPC::SetXER_OV(a == 0x80000000);
+
+  if (inst.Rc)
+    Helper_UpdateCR0(rGPR[inst.RD]);
 }
 
 void Interpreter::subfx(UGeckoInstruction inst)