src: add ofono-iface

Start work on new ofono interface. So far, this detects ofono on dbus
and complains if both mm and ofono are running.

src/manager.h

@@ -27,6 +27,12 @@ enum EG25State {
     EG25_STATE_FINISHING
 };
 
+enum ModemIface {
+    MODEM_IFACE_NONE = 0,
+    MODEM_IFACE_MODEMMANAGER,
+    MODEM_IFACE_OFONO
+};
+
 struct EG25Manager {
     GMainLoop *loop;
     guint reset_timer;
@@ -41,9 +47,11 @@ struct EG25Manager {
     enum EG25State modem_state;
     gchar *modem_usb_id;
 
+    enum ModemIface modem_iface;
     guint mm_watch;
     MMManager *mm_manager;
     MMModem *mm_modem;
+    guint ofono_watch;
 
     GDBusProxy *suspend_proxy;
     int suspend_delay_fd;