aux/indices: include provoking vertex check in prim type conversion

Include provoking vertex checking in u_index_prim_type_convert() to make sure the right primitive type is returned from the generator function.

Fixes google earth running on VMware svga device on hw version 11.

Fixes: cad2026b ("aux/indices: break out primitive type conversion to separate function")

Reviewed-by: Charmaine Lee charmainel@vmware.com