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/libs/cplusplus/CppRewriter.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef CPPREWRITER_H
-#define CPPREWRITER_H
+#pragma once
 
 #include "CppDocument.h"
 #include "LookupContext.h"
@@ -110,5 +109,3 @@ CPLUSPLUS_EXPORT const Name *rewriteName(const Name *name,
                                          Control *control);
 
 } // namespace CPlusPlus
-
-#endif // CPPREWRITER_H