patch 8.0.1625: test_quotestar is flaky when run in GTK GUI

Problem:    Test_quotestar is flaky when run in GTK GUI.
Solution:   Do not call lose_selection when invoked from
            selection_clear_event().

src/gui_gtk_x11.c

@@ -1366,15 +1366,21 @@ key_release_event(GtkWidget *widget UNUSED,
  * Selection handlers:
  */
 
+/* Remember when clip_lose_selection was called from here, we must not call
+ * gtk_selection_owner_set() then. */
+static int in_selection_clear_event = FALSE;
+
     static gint
 selection_clear_event(GtkWidget		*widget UNUSED,
 		      GdkEventSelection	*event,
 		      gpointer		user_data UNUSED)
 {
+    in_selection_clear_event = TRUE;
     if (event->selection == clip_plus.gtk_sel_atom)
 	clip_lose_selection(&clip_plus);
     else
 	clip_lose_selection(&clip_star);
+    in_selection_clear_event = FALSE;
 
     return TRUE;
 }
@@ -7048,8 +7054,11 @@ clip_mch_request_selection(VimClipboard *cbd)
     void
 clip_mch_lose_selection(VimClipboard *cbd UNUSED)
 {
-    gtk_selection_owner_set(NULL, cbd->gtk_sel_atom, gui.event_time);
-    gui_mch_update();
+    if (!in_selection_clear_event)
+    {
+	gtk_selection_owner_set(NULL, cbd->gtk_sel_atom, gui.event_time);
+	gui_mch_update();
+    }
 }
 
 /*

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1625,
 /**/
     1624,
 /**/