Removing sysinstall from 10.x

[Nathan Whitehorn]

For the 9.x branch, we're keeping all 3 installers in the base system, 
but I'd like to remove sysinstall from 10.x now that the releng/9 branch 
has been made, along with its associated forest of crufty old 
dependencies (libdisk, libftpio, etc.). Does anyone have strong reasons 
not to do this? Otherwise I'll consign sysinstall to the attic on Friday 
30 Sept.
-Nathan