vertex_desc.Pool should obviously be used in the 
WINED3DRTYPE_VERTEXBUFFER case instead of index_desc.Pool.

The base version won't suffice anymore as it is not able to upload
palette changes to the drawable in an efficient way for both GDI and
GL. Further the LoadLocation code in RealizePalette isn't needed for
the GDI version as in all cases it works on system memory.