vim-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.
bbb5f8d4c2

src/nvim/move.c

@@ -103,7 +103,7 @@ void reset_cursorline(void)
 }
 
 // Redraw when w_cline_row changes and 'relativenumber' or 'cursorline' is set.
-static void redraw_for_cursorline(win_T *wp)
+void redraw_for_cursorline(win_T *wp)
 {
   if ((wp->w_p_rnu || win_cursorline_standout(wp))
       && (wp->w_valid & VALID_CROW) == 0
@@ -122,7 +122,6 @@ static void redraw_for_cursorline(win_T *wp)
       } else {
         redraw_win_later(wp, SOME_VALID);
       }
-      wp->w_last_cursorline = wp->w_cursor.lnum;
     }
   }
 }

src/nvim/normal.c

@@ -4038,6 +4038,9 @@ static void nv_mousescroll(cmdarg_T *cap)
   } else {
     mouse_scroll_horiz(cap->arg);
   }
+  if (curwin != old_curwin && curwin->w_p_cul) {
+    redraw_for_cursorline(curwin);
+  }
 
   curwin->w_redr_status = true;