pkg/system: exposed functions need a windows equivalent
pkg/system: exposed functions need a windows equivalent

Windows does not have a concept of UID/GID, but rather ACLs and SIDs
which do not map cleanly at all.
Since we've exposed `UID()` and `GID()` for this `StatT`, then we need
something equivalent.

Signed-off-by: Vincent Batts <d01a4772f0cffd3f005a7d7f01c59cd104c7a5fe@hashbangbash.com>

rhatdan/storage,containers/storage,containers/storage,rhatdan/storage,containers/storage,rhatdan/storage