patch 9.0.1435: scrolling too many lines when 'wrap' and 'diff' are set

Problem:    Scrolling too many lines when 'wrap' and 'diff' are set.
Solution:   Only scroll by screenlines for 'diff' when 'wrap' is not set.
            (closes #12211)
diff --git a/src/move.c b/src/move.c
index e8b86ca..77d8b5f 100644
--- a/src/move.c
+++ b/src/move.c
@@ -1763,7 +1763,7 @@
 	|| (byfold && hasAnyFolding(curwin))
 # endif
 # ifdef FEAT_DIFF
-	|| curwin->w_p_diff
+	|| (curwin->w_p_diff && !curwin->w_p_wrap)
 # endif
 	;
 }