regenerate patches for dpkg

also:
- add a runtime dependency on gzip (not a library one, though, as it
does not link against it)
- use the pod2man from the MacPorts perl5 port
- the start-stop-daemon now builds!
- actually describe all the patches in the dpkg Portfile (and reformat
autogen's descriptions of patches to match formatting here)
- modify autogen's gen_patches.sh script to work for dpkg