patch 8.2.4803: WinScrolled not always triggered when scrolling with mouse

Problem:    WinScrolled not always triggered when scrolling with the mouse.
Solution:   Add calls to may_trigger_winscrolled(). (closes #10246)
diff --git a/src/mouse.c b/src/mouse.c
index 4296334..a0c5156 100644
--- a/src/mouse.c
+++ b/src/mouse.c
@@ -1127,6 +1127,7 @@
 	}
 #endif
 	did_scroll = TRUE;
+	may_trigger_winscrolled();
     }
 
     curwin->w_redr_status = TRUE;
@@ -2087,6 +2088,7 @@
     if (curwin != old_curwin && curwin->w_p_cul)
 	redraw_for_cursorline(curwin);
 # endif
+    may_trigger_winscrolled();
 
     curwin->w_redr_status = TRUE;