patch 8.0.0556: getting window position fails if GUI and term possible

Problem:    Getting the window position fails if both the GUI and term
            code is built in.
Solution:   Return after getting the GUI window position. (Kazunobu Kuriyama)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    556,
 /**/
     555,
 /**/