Wholesale conversion to #pragma once

Kudos to cgmb and https://github.com/cgmb/guardonce

Change-Id: Ifa8970734b8d43fd08c9260c645bdb0228633791
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/debugger/debuggericons.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef DEBUGGERICONS_H
-#define DEBUGGERICONS_H
+#pragma once
 
 #include <utils/icon.h>
 
@@ -90,5 +89,3 @@ const Utils::Icon MODE_DEBUGGER_FLAT_ACTIVE({
 
 } // namespace Icons
 } // namespace Debugger
-
-#endif // DEBUGGERICONS_H