optimise away unneeded flag sets

- especially useful for thumb code and larger max block sizes
- can still be improved upon

src/ARMJIT.h

@@ -28,6 +28,7 @@ struct FetchedInstr
         return Instr >> 28;
     }
 
+	u8 SetFlags;
     u32 Instr;
     u32 NextInstr[2];