isisd: reapply patch to fix zebra protocol

Reapply the bits of revision b4e45f6 that pertain to isisd. That is:
  git log -n 1 -p b4e45f6 -- isisd

These were dropped in the merge with the Google ISIS code (14d2bbaa).

The commit message for b4e45f6 is:

    fix zebra protocol after MP-BGP changes

    The previous commits modified both zebra and bgpd for additional
    SAFI field, but not any other routing daemon, which led to zebra
    daemon crashing with failed assertion.
1 file changed