SITL: fixed build with no GCS

libraries/SITL/SIM_Aircraft.cpp

@@ -565,7 +565,7 @@ void Aircraft::update_dynamics(const Vector3f &rot_accel)
     // constrain height to the ground
     if (on_ground()) {
         if (!was_on_ground && AP_HAL::millis() - last_ground_contact_ms > 1000) {
-            gcs().send_text(MAV_SEVERITY_INFO, "SIM Hit ground at %f m/s", velocity_ef.z);
+            GCS_SEND_TEXT(MAV_SEVERITY_INFO, "SIM Hit ground at %f m/s", velocity_ef.z);
             last_ground_contact_ms = AP_HAL::millis();
         }
         position.z = -(ground_level + frame_height - home.alt * 0.01f + ground_height_difference());

libraries/SITL/SIM_Parachute.cpp

@@ -54,7 +54,7 @@ void Parachute::update(const struct sitl_input &input)
     if (pwm >= 1250) {
         if (!deployed_ms) {
             deployed_ms = AP_HAL::millis();
-            gcs().send_text(MAV_SEVERITY_WARNING, "BANG!  Parachute deployed");
+            GCS_SEND_TEXT(MAV_SEVERITY_WARNING, "BANG!  Parachute deployed");
         }
     }
     last_update_us = now;

libraries/SITL/SIM_RF_LightWareSerial.cpp

@@ -32,7 +32,7 @@ bool RF_LightWareSerial::check_synced()
         ssize_t n = read_from_autopilot(buffer, ARRAY_SIZE(buffer) - 1);
         if (n > 0) {
             if (!strncmp(buffer, "www\r\n", ARRAY_SIZE(buffer))) {
-                gcs().send_text(MAV_SEVERITY_INFO, "Slurped a sync thing\n");
+                GCS_SEND_TEXT(MAV_SEVERITY_INFO, "Slurped a sync thing\n");
                 synced = true;
             }
         }

libraries/SITL/SIM_RF_Wasp.cpp

@@ -94,7 +94,7 @@ void RF_Wasp::check_configuration()
             }
         }
         if (!set) {
-            gcs().send_text(MAV_SEVERITY_INFO, "Wasp: unknown setting (%s)", &_buffer[0]);
+            GCS_SEND_TEXT(MAV_SEVERITY_INFO, "Wasp: unknown setting (%s)", &_buffer[0]);
         }
     }