I still do not see why it is not possible to have only one folder dlls/d3dx9/ with the thirteen spec files inside. After all, the vast majority of its code is repeated and it is the same system ctl3d, ctl3d32 and ctl3dv2 use as the three specs are in dlls/ctl3d32
This is not creating subfolders in dlls/d3dx9 but just putting all spec files in it.