Clang: Cleanup IPC code

Change-Id: I29571801b4093337e2c7cc1eec51cfcd07b3bdc5
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/libs/clangbackendipc/filepath.h

@@ -131,6 +131,5 @@ private:
 };
 
 CMBIPC_EXPORT QDebug operator<<(QDebug debug, const FilePath &filePath);
-void PrintTo(const FilePath &filePath, ::std::ostream* os);
 
 } // namespace ClangBackEnd