this change fixes the FTBFS on Debian hurd-* and kfreebsd-*.
* Update build-dependencies to permit tcl8.6. Closes:#818475.
* Replace ad-hocery with use of offsetof/typeof. Closes:#812718.
this change fixes the FTBFS on Debian hurd-* and kfreebsd-*.
* Update build-dependencies to permit tcl8.6. Closes:#818475.
* Replace ad-hocery with use of offsetof/typeof. Closes:#812718.