put qmin in params.cxx.opt when missing in params.cxx
put qmin in params.cxx.opt when missing in params.cxx

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