Explicitly include std::bind functions

Should fix compile

src/wayland/idle_interface.cpp

@@ -25,6 +25,7 @@ License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QTimer>
 
+#include <functional>
 #include <wayland-server.h>
 #include <wayland-idle-server-protocol.h>