patch 9.1.0526: Unwanted cursor movement with pagescroll at start of buffer

Problem:  Cursor is moved to bottom of window trying to pagescroll when
          already at the start of the buffer (Asheq Imran, after v9.1.0357)
Solution: Don't move cursor when buffer content did not move.
          (Luuk van Baal)

closes: #15139

Signed-off-by: Luuk van Baal <luukvbaal@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    526,
 /**/
     525,
 /**/