fix sanitizer build on debian9
On my debian 9 machine with
gcc (Debian 7.2.0-18) 7.2.0, the unit tests exhibit --enable-sanitize build failures, mostly because their talloc contexts aren't setup properly. On our current deb8 build slave with an earlier gcc, these don't show. Fix the sanitizer failures so we can easily move to deb9 if we so desire.