Also change check_for_apparmor() to allow easier testing by optionally
specifying alternative locations for /proc/filesystems and /proc/mounts
as parameter.
Note that the code in check_for_apparmor() differs from what the comment
says - valid_path() only does syntax checks, but doesn't check if the
directory exists. I added a comment saying exactly that.
Acked-by: Steve Beattie <steve@nxnw.org>
