Make a copy of __progname on start to avoid setproctitle clobbering it
later. Check if the OS supports __progname and emulate if unavailable.
- from OpenSSH.
Thanks to Paul B. Henson for reporting the setproctitle emulation issue
and Jonas 'Sortie' Termansen for suggesting __progname emulation.

update manpage and add more fatal logging

This reworks a few of the common patches on Debian and Gentoo to be a
little nicer, and changes the patches to be per-fix rather than
per-file.