Upstream glibc writes this:
* The “ip6-dotint” and “no-ip6-dotint” resolver options, and the
corresponding RES_NOIP6DOTINT flag from <resolv.h> have been removed.
“no-ip6-dotint” had already been the default, and support for the
“ip6-dotint” option was removed from the Internet in 2006.
Lack of Internet support means that we can safely remove this from our glibc as well.
Relevant upstream commit:
Author: Florian Weimer <firstname.lastname@example.org>
Date: Fri Oct 7 13:55:47 2016 +0200
resolv: Remove RES_NOIP6DOTINT and its implementation
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.