oleaut32: Use correct bitpattern if referenced type is not user defined.

This reduces the diff between the TLB file output by Wine and Windows XP
when running the typelib test module.

dlls/oleaut32/typelib2.c

@@ -1109,7 +1109,7 @@ static int ctl2_encode_typedesc(
 			mix_field = typedata[0]>>16;
 			break;
 		    default:
-			mix_field = 0x7fff;
+			mix_field = ((typedata[0] >> 16) == 0x7fff) ? 0x7fff : 0x7ffe;
 			break;
 		}
 	    }