patch 8.1.0856: when scrolling a window the cursorline is not always updated

Problem:    When scrolling a window other than the current one the cursorline
            highlighting is not always updated. (Jason Franklin)
Solution:   Call redraw_for_cursorline() after scrolling.  Only set
            w_last_cursorline when drawing the cursor line.  Reset the lines
            to be redrawn also when redrawing the whole window.

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    856,
 /**/
     855,
 /**/