tbnexthop.{cc,h} now contains setsockopts to install "ipfw fwd" rules.

<netinet/ip_fw.h> has changed from FBSD 4.3 to 4.5 . Because boss has 4.3,
compiling ipfw code on boss and running it on an experimental
node doesn't work. Therefore, I now have a cvs checked in local copy of
the 4.5 version of the file.

nseinput.tcl now finds the CPU cycle speed from /var/run/dmesg.boot and
passes the info to nse's RT scheduler which keeps track of real time
using the TSC. The same info can be obtained by PERFMON ioctls but the
kernel boot time measurement of the cpu cycle speed is more accurate than
what perfmon can report