Function dt_load_libs_sort

* Perform a topological sorting of all the libraries found across the entire * dt_lib_path. Once sorted, compile each one in topological order to cache its * inlines and translators, etc. We silently ignore any missing directories and * other files found therein. We only fail (and thereby fail dt_load_libs()) if * we fail to compile a library and the error is something other than #pragma D