AP_AccelCal: replace header guard with pragma once

libraries/AP_AccelCal/AP_AccelCal.h

@@ -1,5 +1,4 @@
-#ifndef __AP_ACCELCAL_H__
-#define __AP_ACCELCAL_H__
+#pragma once
 
 #include <GCS_MAVLink/GCS_MAVLink.h>
 #include "AccelCalibrator.h"
@@ -83,5 +82,3 @@ private:
     virtual void _acal_event_cancellation() {};
     virtual void _acal_event_failure() {};
 };
-
-#endif

libraries/AP_AccelCal/AccelCalibrator.h

@@ -11,9 +11,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
+#pragma once
 
-#ifndef __ACCELCALIBRATOR_H__
-#define __ACCELCALIBRATOR_H__
 #include <AP_Math/AP_Math.h>
 #include <AP_Math/vectorN.h>
 
@@ -144,4 +143,3 @@ private:
     void calc_jacob(const Vector3f& sample, const struct param_t& params, VectorP& ret) const;
     void run_fit(uint8_t max_iterations, float& fitness);
 };
-#endif //__ACCELCALIBRATOR_H__