/usr/lib/tk8.5/tkConfig.sh is in tk8.5-dev 8.5.15-2ubuntu3.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 | #! /bin/sh
. /usr/lib/`dpkg-architecture -qDEB_HOST_MULTIARCH`/tk8.5/tkConfig.sh
|