updated for version 7.4.185
Problem:    Clang gives warnings.
Solution:   Adjust how bigness is set. (Dominique Pelle)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 70cdd34..465fb9e 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -4099,12 +4099,12 @@
      * 'scroll' */
     if (eap->forceit)
 	bigness = curwin->w_height;
-    else if (firstwin == lastwin)
-	bigness = curwin->w_p_scr * 2;
 #ifdef FEAT_WINDOWS
-    else
+    else if (firstwin != lastwin)
 	bigness = curwin->w_height - 3;
 #endif
+    else
+	bigness = curwin->w_p_scr * 2;
     if (bigness < 1)
 	bigness = 1;