security: Do not restore kernel and initrd labels

security: Do not restore kernel and initrd labels

Kernel/initrd files are essentially read-only shareable images and thus
should be handled in the same way. We already use the appropriate label
for kernel/initrd files when starting a domain, but when a domain gets
destroyed we would remove the labels which would make other running
domains using the same files very unhappy.

https://bugzilla.redhat.com/show_bug.cgi?id=921135

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>