I'm not sure against what branch to propose this, please let me know what's best. I'm proposing the same changes in Ubuntu to fix #1850699
In Ubuntu we are trying to switch all packages to use iproute2 where we can. Upstream bind9 did some work in this area already.
I don't have access to a solaris box to check exactly what ifconfig -au produces, but I think the idea is similar to ip addr.