Removal of security/root_plug.c

[Anne Thrax <foobarfoobarfoobar@gmail.com>]

Hello all,

Apparently security/root_plug.c was written for a Linux Journal article,
and while it does do a good job of explaining LSM, I don't see much use for
it in the mainstream kernel. I suggest that it be removed, because I don't
think that it serves much purpose. I doubt that anyone actually uses this,
for if they did, I think that it would be modified and have many additions.
Even the author states that it is just a starting point. Maybe the article
(if Linux Journal is okay with it) along with the code should be moved to
Documentation/?