Fix compile error when not using Modem Manager.

src/suspend.c

@@ -28,12 +28,15 @@ static gboolean check_modem_resume(struct EG25Manager *manager)
 {
     manager->modem_recovery_timer = 0;
 
+#ifdef HAVE_MMGLIB
     if (manager->mm_modem) {
         resume_ok(manager);
-    } else {
+        return FALSE;
+    }
+#endif
+
     g_message("Modem wasn't probed in time, restart it!");
     modem_reset(manager);
-    }
 
     return FALSE;
 }