No, we should be able to compile withiout mesa if we did before my patch. Unfortunately I dont know how to do this (I did warn alongside my patch) - Is there any chance you could work out how dlls/ddraw handles this issue so we can do the same.
I suspect for non-gl enabled machines (until we go via a HAL) we should hava a d3d8.dll which just returns an error on the Direct3DCreate8 call.
Jason