Reuse cached filesystems for layers
Reuse cached filesystems for layers

This commit applies the same criteria for reusing extracted layer
filesystems than the one used for the whole image extracted filesystem

Signed-off-by: David Cassany <b4d9261906f99e63d6e6b12d77f2aa5f7208f479@suse.de>

GoogleContainerTools/container-diff,nkubala/container-diff,GoogleContainerTools/container-diff,nkubala/container-diff,nkubala/container-diff,GoogleContainerTools/container-diff