This is a test program, this will probably be integrated into su daemon.
This hides su by bind-mounting something (/system) over /sbin, so that
there is no /sbin/su binary.
Usage:
hidesu /proc/<one pid of the namespace>/ns/mnt
This uses the fact that when a program wants access to /sdcard, zygote
does this using mount namespaces, so every program accessing /sdcard
will be in a custom mount namespace, that can be modified.