Looks like QtCreator should add $$system_path() automatically when adding a library to a project

The bug is described here on Qt forum:

https://forum.qt.io/topic/97264/error-link2019-is-resolved-when-using-explicit-paths-for-library-path

Adding a library to a project by QtCreator automatic tools, adds some lines to project `*.pro` file described on above link. Looks like QtCreator should use `$$system_path()` when adding a library to a project.