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/coreplugin/generatedfile.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef CORE_GENERATEDFILE_H
-#define CORE_GENERATEDFILE_H
+#pragma once
 
 #include "coreplugin/id.h"
 
@@ -88,5 +87,3 @@ private:
 typedef QList<GeneratedFile> GeneratedFiles;
 
 } // namespace Core
-
-#endif // CORE_GENERATEDFILE_H