For allocations, we need to support stencil-only and separate stencil
resources. For mapping, we need to support software tiling and
packing/unpacking for separate stencil resources.
Now tells Gallium that ilo supports primitive restart.
Updated ilo_draw_vbo to be able to check that the indexed
primitive being rendered can actually be supported in HW. If not,
will break up into individual prims similar to what Mesa does.
[olv: a minor fix after rebasing and formatting]