Updating of DTraceToolkit for FreeBSD

[George Neville-Neil]

Hi,

Note that I'll be updating bits of the DTraceToolkit in our cddl/contrib 
directory to work
with FreeBSD.  Changes will include removing the dependency on ksh in 
all scripts that I touch
along with the conversion of probes to match those on FreeBSD.

I am working exclusively in HEAD for now.  Please try the scripts on 
your own systems and
let me know if they work or if you have problems.  The changes can be 
tracked via the commits
mailing list.  To kick off the fun I modified rwsnoop to run on FreeBSD.

Note that until I or someone else adds a few more things (like the fds 
array) some of the scripts
will not work exactly the same on Illumos, MacOS and FreeBSD, but that 
is the eventual goal.

Best,
George