rsc pointsout that if I don't mind taking longer to make it all work, I
can do the following:

	- put out new binaries that write both "oldheaders" and "headers"
	- put out new kernel with both
	- put out new binaries with just "headers"
	- put out new kernel with just "headers"

And we aren't left with the ++ for all time.

I may do that instead.  It just means that I have to delay putting out the
new udp.c for a while.  I'll do it...