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/valgrind/xmlprotocol/modelhelpers.h

@@ -24,8 +24,7 @@
 **
 ****************************************************************************/
 
-#ifndef LIBVALGRIND_PROTOCOL_MODELHELPERS_H
-#define LIBVALGRIND_PROTOCOL_MODELHELPERS_H
+#pragma once
 
 #include <QtGlobal>
 
@@ -42,5 +41,3 @@ QString toolTipForFrame(const Frame &frame);
 
 } // namespace XmlProtocol
 } // namespace Valgrind
-
-#endif // LIBVALGRIND_PROTOCOL_MODELHELPERS_H