[gtk] GDK W32: Fix a missing weak referencing

[LRN <ruslanizhb src gnome org>]

commit 20f12f9ed7260838bbf82d722e7ed1f85ca2eda5
Author: Руслан Ижбулатов <lrn1986 gmail com>
Date:   Wed Apr 11 16:39:34 2018 +0000

    GDK W32: Fix a missing weak referencing
    
    The changes in a82d67bb7d9290693e8d8c503e65694bb62b44ca didn't
    preserve a g_object_weak_ref() call that we need to ensure the
    objects in hash map don't become stale. Fix this.

 gdk/win32/gdkcursor-win32.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gdk/win32/gdkcursor-win32.c b/gdk/win32/gdkcursor-win32.c
index 95bcb334a8..b1545a67ba 100644
--- a/gdk/win32/gdkcursor-win32.c
+++ b/gdk/win32/gdkcursor-win32.c
@@ -1534,6 +1534,7 @@ gdk_win32_display_get_win32hcursor (GdkWin32Display *display,
 
   if (win32hcursor != NULL)
     {
+      g_object_weak_ref (G_OBJECT (cursor), gdk_win32_cursor_remove_from_cache, display);
       g_hash_table_insert (win32_display->cursors, cursor, win32hcursor);
 
       return win32hcursor;