C++ modernize: Pragma once (#6264)

* Migrate cpp headers to pragma once

src/porting_android.h

@@ -16,8 +16,8 @@ You should have received a copy of the GNU Lesser General Public License along
 with this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
-#ifndef __PORTING_ANDROID_H__
-#define __PORTING_ANDROID_H__
+
+#pragma once
 
 #ifndef __ANDROID__
 #error this include has to be included on android port only!
@@ -77,5 +77,3 @@ int getInputDialogState();
 std::string getInputDialogValue();
 
 }
-
-#endif