weston-editor: Close the data source after sending

We're leaking the fd when sending cut'n'paste.  Failure to close can also
makes the other end unhappy because it doesn't know the paste is finished.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Yong Bakos <ybakos@humanoriented.com>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>

clients/editor.c

@@ -576,6 +576,8 @@ data_source_send(void *data,
 
 	if (write(fd, editor->selected_text, strlen(editor->selected_text) + 1) < 0)
 		fprintf(stderr, "write failed: %m\n");
+
+	close(fd);
 }
 
 static void