This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
do it themselves. (Some of these programs actually depended on this
beyond compiling the definition of struct ifinfo!) Also fix up some
other #include messes while we're at it.
