Quieten newer compilers with MORE CONST CORRECTNESS. (except, haha, gengetopt doesn't generate const-correct function prototypes. Happy happy joy joy. Put in an explicit cast when calling cmdline_parser().) Adjust gengetopt.in and Makefile to support both old (2.19) and new (2.22) versions of gengetopt. This only really means that we've lost -H as a help switch; --help still works.