[gtk+/gtk-3-22] quartz: Implement gtk_clipboard_get_selection

[Philip Chimento <pchimento src gnome org>]

commit e338b4589d353c610352feef4054eae902117436
Author: Philip Chimento <philip chimento gmail com>
Date:   Wed Nov 2 23:37:29 2016 -0700

    quartz: Implement gtk_clipboard_get_selection
    
    This function is trivial and can be copied from the X11 implementation.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=772281

 gtk/gtkclipboard-quartz.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkclipboard-quartz.c b/gtk/gtkclipboard-quartz.c
index a51c46d..fec31f5 100644
--- a/gtk/gtkclipboard-quartz.c
+++ b/gtk/gtkclipboard-quartz.c
@@ -1239,3 +1239,17 @@ _gtk_clipboard_store_all (void)
       list = list->next;
     }
 }
+
+/**
+ * gtk_clipboard_get_selection:
+ * @clipboard:
+ *
+ * Since: 3.22
+ */
+GdkAtom
+gtk_clipboard_get_selection (GtkClipboard *clipboard)
+{
+  g_return_val_if_fail (GTK_IS_CLIPBOARD (clipboard), GDK_NONE);
+
+  return clipboard->selection;
+}