Removed sgn.hpp with only on (invalid) use in the codebase

corsika/framework/utility/sgn.hpp

-/*
- * (c) Copyright 2018 CORSIKA Project, corsika-project@lists.kit.edu
- *
- *
- * This software is distributed under the terms of the GNU General Public
- * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
- * the license.
- */
-
-#pragma once
-
-namespace corsika {
-
-  //! sign function without branches
-  template <typename T>
-  static int sgn(T val) {
-    return (T(0) < val) - (val < T(0));
-  }
-
-} // namespace corsika