AP_NavEKF2: replace header guard with pragma once

libraries/AP_NavEKF2/AP_NavEKF2.h

@@ -18,9 +18,7 @@
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-
-#ifndef AP_NavEKF2_Tuning
-#define AP_NavEKF2_Tuning
+#pragma once
 
 #include <AP_Math/AP_Math.h>
 #include <AP_Param/AP_Param.h>
@@ -341,5 +339,3 @@ private:
     const uint8_t gndGradientSigma;     // RMS terrain gradient percentage assumed by the terrain height estimation
     const uint8_t fusionTimeStep_ms;    // The minimum time interval between covariance predictions and measurement fusions in msec
 };
-
-#endif //AP_NavEKF2

libraries/AP_NavEKF2/AP_NavEKF2_core.h

@@ -17,9 +17,7 @@
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-
-#ifndef AP_NavEKF2_core
-#define AP_NavEKF2_core
+#pragma once
 
 #pragma GCC optimize("O3")
 
@@ -934,5 +932,3 @@ private:
     // vehicle specific initial gyro bias uncertainty
     float InitialGyroBiasUncertainty(void) const;
 };
-
-#endif // AP_NavEKF2_core