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/projectexplorer/jsonwizard/jsonwizardfactory.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef JSONWIZARDFACTORY_H
-#define JSONWIZARDFACTORY_H
+#pragma once
 
 #include "../projectexplorer_export.h"
 
@@ -123,5 +122,3 @@ private:
 };
 
 } //namespace ProjectExplorer
-
-#endif // JSONWIZARDFACTORY_H