overlayutils: Add fastpath for userxattr check
overlayutils: Add fastpath for userxattr check

Cleaning up TODO's. If we're on >= 5.11 we need userxattr so check
the kernel version to skip the manual check via mounting. It feels
odd to use contrib/seccomp here but the alternative is pulling that
kernel parsing code out into the main pkgs. Another is using the moby
parser but that's in moby/moby which is also a dep we don't want here..

Signed-off-by: Danny Canter <df4bf92e16bbb7396c50d637f6b7ad9a4c8c274c@dcantah.dev>

mikebrow/containerd,estesp/containerd,thaJeztah/containerd,mikebrow/containerd,estesp/containerd,containerd/containerd,thaJeztah/containerd,containerd/containerd