Add sssd support for sudo

[SergeiDiachenko]

Issue Report

Feature Request

Environment

What hardware/cloud provider/hypervisor is being used to run Container Linux?
Amazon EC2

Desired Feature

I joined CoreOS in FreeIPA domain. SSSD on CoreOS configured to get users and sudo rules from FreeIPA. FreeIPA users can authenticate on CoreOS, but FreeIPA sudo rules don't apply.
I believe the reason is that sudo is built without "--with-sssd" flag. As I see in log files, sssd fetches sudo rules from FreeIPA, but sudo doesn't ask sssd.

Other Information

https://groups.google.com/forum/#!topic/coreos-dev/JbefCb309LI
#1856

[ajeddeloh]

It looks like this is already done and will be in the next alpha. See coreos/coreos-overlay#3210. Please reopen if 1772.0.0 doesn't fix this for you.