Drop KERBEROS_HTTP_HOST configuration handle
    
    In 7288d464a2de48c49a7ca290aa4a5fa453baa4e1, it was assumed that a
    default realm was configured on clients when it was not.  This caused
    lookup failures because GSSAPI canonicalized to an empty realm string.
    However, since GSSAPI will automatically select the client-requested
    principal if it exists in the ccache, there's no need for the name
    logic at all.