remote-desktop: Add dummy remote selection source

It doesn't yet fetch data from the remote desktop session, but hooks up
correctly.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1552>

src/core/meta-selection-source-remote.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2020 Red Hat
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ */
+
+#ifndef META_SELECTION_SOURCE_REMOTE_H
+#define META_SELECTION_SOURCE_REMOTE_H
+
+#include "backends/meta-remote-desktop.h"
+#include "meta/meta-selection-source.h"
+
+#define META_TYPE_SELECTION_SOURCE_REMOTE (meta_selection_source_remote_get_type ())
+G_DECLARE_FINAL_TYPE (MetaSelectionSourceRemote,
+                      meta_selection_source_remote,
+                      META, SELECTION_SOURCE_REMOTE,
+                      MetaSelectionSource)
+
+MetaSelectionSourceRemote * meta_selection_source_remote_new (MetaRemoteDesktopSession *session,
+                                                              GList                    *mime_types);
+
+#endif /* META_SELECTION_SOURCE_REMOTE_H */