This alter the current state machine by adding S_HANDSHAKE as the initial state. There, we ensure we did the handshake and we check SNI. ATM we simply continue in S_OPEN, but later we can add virtual host checks there, and skip to S_INITIALIZING with an error state if the client is accessing a wrong host.

other functions that aren't macros anymore. LOG went under a rename to logs because log is a builtin (the math function), or so gcc says.

and while there replace SAFE_SETENV with an inline function. LOG is more difficult to transform into an inline function, given the string concatenations it does. The other LOG* and FATAL macros are fine as they already are.

todo was initially there for an optimization: don't loop to MAX_USERS when you know the upper limit is todo.

SIGHUP is sent when the tty is detached and by default kills the process. When we run in the background we don't care anymore about the tty, so it should be safe for us to ignore SIGHUP. (frankly, I expected daemon(3) to do stuff like this for us).