MFC r279819:

Fix CARP when in use in a HyperV environment:

• Bump link state when stopping or starting the interface;
• Don't handle SIOCGIFADDR specially, similar to r277103.

This change is based on a previous revision from Andy Zhang
(Microsoft) who did the diagnostic work and many thanks to
them for their help in supporting the HyperV work.

PR: kern/187203