selinux: Remove audit dependency

Auditing comes with a lot of overhead due to string assembly via
vsnprintf. It isn't actually needed to make SELinux work, so remove
SELinux's artificial dependency on it to make it possible to use SELinux
without the unneeded overhead.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Danny Lin <danny@kdrag0n.dev>