pinentry requires getopt_long, but no implementation is provided for those
systems which do not include it in libc. In my particular instance, that was
HP-UX 11.11

I used GNUlib to add the getopt-gnu module (using the default lib and m4
directories) and modified configure.ac and a couple of Makefile.am to use it. I
don't have QT or GTK+ installed, so I'm not sure if those Makefile.am need
modification as well.