the struct kmemstats that describes the type.
This allows subsystems to declare their malloc types locally
and <sys/malloc.h> doesn't need tweaked everytime somebody
gets an idea. You can even have a type local to a lkm...
I don't know if we really need the longdesc, comments welcome.
TODO: There is a single nit in ext2fs, that will be fixed later,
and I intend to remove all unused malloc types and distribute
the rest closer to their use.