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/tools/clangbackend/ipcsource/sourcelocation.h

@@ -23,8 +23,7 @@
 **
 ****************************************************************************/
 
-#ifndef CLANGBACKEND_SOURCELOCATION_H
-#define CLANGBACKEND_SOURCELOCATION_H
+#pragma once
 
 #include <clang-c/Index.h>
 
@@ -75,5 +74,3 @@ bool operator==(const SourceLocation &first, const SourceLocation &second);
 void PrintTo(const SourceLocation &sourceLocation, ::std::ostream* os);
 
 } // namespace ClangBackEnd
-
-#endif // CLANGBACKEND_SOURCELOCATION_H