Re: [Libguestfs] [nbdkit PATCH] main: More idiomatic use of getopt_long

Prefer named constants over magic numbers in the 'struct option' list, and expand the list of enums for long-only options so that the call to getopt_long() can switch directly to every option, rather than needing a lengthy if/else chain that grows for every new long option. Patch best viewed with whitespace changes ignored.