Was temporarly disabled during the transition to real privsep. While here, fix a memory leak when using `require client ca'. Also, avoid leaking info about the parent address space layout to server processes by not sending pointer values.

It uses the 'common' proc.c from various OpenBSD-daemons. gmid grew organically bit by bit and it was also the first place where I tried to implement privsep. It wasn't done very well, in fact the parent process (that retains root privileges) just fork()s a generation of servers, all sharing *exactly* the same address space. No good! Now, we fork() and re-exec() ourselves, so that each process has a fresh address space. Some features (require client ca for example) are temporarly disabled, will be fixed in subsequent commits. The "ge" program is also temporarly disabled as it needs tweaks to do privsep too.

breaks on some distro and needs further investigations; it's not that interesting fortunately.

I really want to get rid of the `executor' process hack for CGI scripts and its escalation to allow fastcgi and proxying to work on non-OpenBSD. This drops the CGI support and the `executor' process entirely and is the first step towards gmid 2.0. It also allows to have more secure defaults. On non-OpenBSD systems this means that the sandbox will be deactivated as soon as fastcgi or proxying are used: you can't open sockets under FreeBSD' capsicum(4) and I don't want to go thru the pain of making it work under linux' seccomp/landlock. Patches are always welcome however. For folks using CGI scripts (hey, I'm one of you!) not all hope is lost: fcgiwrap or OpenBSD' slowcgi(8) are ways to run CGI scripts as they were FastCGI applications. fixes for the documentation and to the non-OpenBSD sandboxes will follow.