Raw FFI bindings and vendored build integration for the Parma Polyhedra Library (PPL).
Default feature set builds PPL with GMP coefficients. Enable `i64` for the integer backend and `pic` for
`-fPIC`. Building requires autotools and a C++ toolchain.
Vendored PPL source snapshot:
`vendor/ppl-92d0704d3309d55f39a647595f8383b86fcd57e1.tar.gz`
License: GPL-3.0-or-later (inherited from PPL).