Refactor: BLI_path_util (split out app directory access)

This module is intended for path manipulation functions
but had utility functions added to access various directories.

source/gameengine/Ketsji/KX_PythonInit.cpp

@@ -133,6 +133,7 @@ extern "C" {
 #include "BKE_main.h"
 #include "BKE_global.h"
 #include "BKE_library.h"
+#include "BKE_appdir.h"
 #include "BLI_blenlib.h"
 #include "GPU_material.h"
 #include "MEM_guardedalloc.h"