err/warn is not available on some systems (unfortunately!) and in any case don't play well with our daemon mode (that closes std{in,out,err}). Use our fatal that is daemon-aware.

we don't fork anymore in that process, so the flag is extra.

cgi.c wasn't really needed; it better to group all the server related functions together, cgi or not. Now gmid.c contains only startup and utility code.