Make all fre_*() functions no-ops if pointer is NULL
Make all fre_*() functions no-ops if pointer is NULL

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs