A macro and some declarations from pre-release were left in
`options.h`; since I decided on using getopt and not my own
options parser, it doesn't do anything and might confuse
contributors.

Additionally, a not-entirely-finished clause to check for the
presence of `sysexits.h` was left in the configure script.  I
think I started implementing the whole sysexits thing before release
then changed my mind.  And I might change my mind again and
re-implement them.  I'm not sure.