Fix ipfw/dnctl detection

[meka_tilda.center]

Summary

This diff fixes ipfw/dnctl detection. The bug it fixes is that running "dnctl" vs "/sbin/dnctl" gives different results.

[kp]

It looks like patch does two different things. That really needs to be two separate commits. One to add the dnctl startup script, and one to fix the dnctl/ipfw detection.

sbin/ipfw/main.c

685

That catches a problem, but I believe the usual way of fixing this is with basename(3).
That'll be a lot simpler than this string manipulation.

BASENAME(3)             FreeBSD Library Functions Manual             BASENAME(3)

NAME
     basename – extract the base portion of a pathname

SYNOPSIS
     #include <libgen.h>

     char *
     basename(char *path);

DESCRIPTION
     The basename() function returns the last component from the pathname
     pointed to by path, deleting any trailing ‘/’ characters.