removed a warning

include/ACGL/OpenGL/Objects/Shader.hh

@@ -90,7 +90,7 @@ protected:
      * - Add custom source content
      * - Call addSource(...) with your source content
      */
-    virtual void processPragma(std::vector<std::string> const& _tokens) { }
+    virtual void processPragma(std::vector<std::string> const& /*_tokens*/) { }
 
     /**
      * @brief reads in a source file from file system