CFG: raw socket locking

[Sam Leffler]

http://www.freebsd.org/~sam/rawsock.patch

This locks the raw socket protocol control blocks using equivalent 
techniques to those used for udp, etc.  There is one code restructuring 
done to simplify this work; equivalent to the one I added for udp.

Note this change also removes the rip_olddiverterror sysctl.  It was marked 
as "to be removed".  I'll probably leave it alone and/or remove it in a 
separate pass.

	Sam