I hadn't seen the bugzilla yet, though I know the issue. See patch 1/2, the current approach is to use RngLibTimerLib if the build-time configuration indicates. This isn't recommended but sufficient for building for platforms which require the library class - I think OpensslLib has a dependency. For the same reason, the RngDxe driver is only compiled with the same build definition, because there's no good point to advertising RNG support through the protocol when it's low quality.

Regards,
Benjamin