td_lib contains common library procedures which are shared among Thomas
Dickey's 'ded' and 'cm_tools' utilities, among others.

Note that this is only a build-time dependency of 'ded' and 'cm_tools'.
The SlackBuild will create a package for it, but you do not need to
install it unless you want to.  As long as the compiled source directory
is alongside the 'ded' and/or 'cm_tools' directories, they will build.