v1.16.3

drivers/platformLChown: rm os.Lstat call
drivers/platformLChown: return early
drivers/chown: use pwalk.Walk
vendor: bump selinux to 1.4.0
pkg/system: return nil explicitly
pkg/mount.RecursiveUnmount(): don't call Mounted()
pkg/system.EnsureRemoveAll: don't call Mounted
devmapper: no need to wrap Mount errors
pkg/mount: wrap mount/umount errors
pkg/mount: drop solaris and freebsd support
pkg/mount: mountinfo parser speed up
pkg/system/[l]stat_unix: wrap errors in PathErro