draw: Pass-through pipe_buffer::max_index to translate.

draw: Pass-through pipe_buffer::max_index to translate.

max_index must be observed to prevent crashes due to bad index data.

I've been using this patch for some time without regressions.

Some places, where we use internal vertex buffer, it is not entirely
clear what max_index should be, so passing just ~0 to avoid regressions
for now.