permissions centrally and a setuid root mount utility just breaks
its security. There was no new breakage in practice because
mfdosfs_mount() still checks the ruid.
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.
