os/user: make Lookup* functions properly handle ENOENT
The libc docs say that these functions can return ENOENT, and
per issue #67912, this does happen in practice sometimes. Handle
both the ENOENT and !found cases the same way, for Lookup,
LookupId, LookupGroup, LookupGroupId.
Fixes #67912
Change-Id: I993935af44c83ad785b6cd735fc313a3647daa19
Reviewed-on: https://go-review.googlesource.com/c/go/+/591555 Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Michael Pratt <mpratt@google.com>