set them as global vars; rename foreground -> debug

server_configure_done is the code we ran in IMSG_RECONF_END splitted in a separate functions. This is all needed for ge.c which doesn't do privsep but needs to bootstrap the server process.

so that ge can provide its own log_request without requiring a separate logger process.

it's better than the previous Makefile.depend approach since this automatically adapts to the included headers without requiring manual intervention to regen the list.