AP_Vehicle: don't do any GCS stuff in delay callback if we're Replay

We haven't initialised the GCS at all, so it's not a great idea to
update_receive() and the like.

libraries/AP_Vehicle/AP_Vehicle.cpp

@@ -173,6 +173,11 @@ void AP_Vehicle::get_common_scheduler_tasks(const AP_Scheduler::Task*& tasks, ui
  */
 void AP_Vehicle::scheduler_delay_callback()
 {
+#if APM_BUILD_TYPE(APM_BUILD_Replay)
+    // compass.init() delays, so we end up here.
+    return;
+#endif
+
     static uint32_t last_1hz, last_50hz, last_5s;
 
     AP_Logger &logger = AP::logger();