Module xattr signatures

[Rusty Russell <rusty@rustcorp.com.au>]

Hi all,

        Had a talk with Mimi, and IMA still wants xattr signatures on
modules like they have for other files with EVM.  With Kees' patches now
merged into my modules-wip branch (warning, rebases frequently), this
should be pretty simple.  Dmitry?

        The question of whether this falls back to appended signatures
if there's no xattr support, or whether we fix cpio depends on whether
someone is prepared to do the latter.  As Mimi points out, AIX, bsd,
solaris all have versions of cpio that support extended attributes, as
does the bsdcpio Debian package, for example.

Thanks,
Rusty.