u_primconvert: add primitive restart support

u_primconvert: add primitive restart support

This add primitive restart support to the prim conversion.

This involves changing the API for the translate functions
as we need to pass the prim restart index and the original
number of indices into the translate functions.

primitive restart is support for quads, quad strips
and polygons.

This deal with the case where the actual number of output
primitives is less than the initially calculated number,
by filling the rest of the output primitives with the restart
index, the other option is to reduce the output prim number,
but that will make the generator code a bit messier.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>