This will not make any of object files that LINT create change; there
might be differences with INET disabled, but hardly anything compiled
before without INET anyway. Now the 'obvious' things will give a
proper error if compiled without inet - ipx_ip, ipfw, tcp_debug. The
only thing that _should_ work (but can't be made to compile reasonably
easily) is sppp :-(
This commit move struct arpcom from <netinet/if_ether.h> to
<net/if_arp.h>.
volatile to use outside of splclock(). microtime() is probably too
expensive to use for every i/o. However, setting ifi_lastchange for
every i/o is just wrong according to the comment about ifi_lastchange
in <net/if.h>. It is set then for atm, fddi and the latest version
of ppp.)
