A number of vertex buffer fields like NormalPtr, FogCoordPtr, etc are really

A number of vertex buffer fields like NormalPtr, FogCoordPtr, etc are really
just aliases for members of the VB->AttribPtr[] array.
Begin replacing FogCoordPtr with VB->AttribPtr[_TNL_ATTRIB_FOG], and similarly
for NormalPtr, TexCoordPtr, PointSizePtr, etc.