Commit 12c7541f1f updated the
opencontainers/selinux dependency to v1.3.1, which had a breaking
change in the errors that were returned.
Before v1.3.1, the "raw" `syscall.ENOTSUP` was returned if the
underlying filesystem did not support xattrs, but later versions
wrapped the error, which caused our detection to fail.
This patch uses `errors.Is()` to check for the underlying error.
This requires github.com/pkg/errors v0.9.1 or above (older versions
could use `errors.Cause()`, but are not compatible with "native"
wrapping of errors in Go 1.13 and up, and could potentially cause
these errors to not being detected again.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>