patch 9.0.0917: the WinScrolled autocommand event is not enough

Problem:    The WinScrolled autocommand event is not enough.
Solution:   Add WinResized and provide information about what changed.
            (closes #11576)
diff --git a/src/gui.c b/src/gui.c
index 45747ef..585ead0 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -5097,7 +5097,7 @@
     }
 
     if (!finish_op)
-	may_trigger_winscrolled();
+	may_trigger_win_scrolled_resized();
 
 # ifdef FEAT_CONCEAL
     if (conceal_update_lines