MFH: r531791 r531792

Update to 9.11.18 & 9.16.2.

Changes: https://downloads.isc.org/isc/bind9/9.16.2/RELEASE-NOTES-bind-9.16.2.html
Changes: https://downloads.isc.org/isc/bind9/9.11.18/RELEASE-NOTES-bind-9.11.18.html