Remove rxgk_SetConfiguration

This RXS op is a hack to support an rxkad-only configuration knob,
whether krb5 principal names with dots in the first component are allowed.
This should not be an issue when GSSAPI names are used.

Change-Id: Ib83b21e20d0f9cf93ae5d885a3595f95b8313b3f
Fix call number vector handling

Always send the full vector; check server-side that the length
matches what we're expecting.

Change-Id: I664fec26a12e3caf2ea450e7db5967d3bceaed05
Use rx connection accessors properly

Don't go grubbing around in the private headers; that's not nice.

Change-Id: I83c04e8de20ef56121660628377eabe4c5105ac6
call numbers are signed?

Change-Id: Iff26900d8cb7ec5466877a49600ed01b49132f0f