add -ltinfo to Makefile.am, resolve #138

[fancywriter]

For me this solved #138, after this one added line it builds correctly. Correct me if I have done something wrong.

[maxatka]

Maybe it's not so perfect solution, to add explicitly the lib to flags.
Why not to use pkg-config and switch to
https://autotools.io/pkgconfig/pkg_check_modules.html
In this case, your system will tell you all about flags, not only for linking.

[Polynomial-C]

I suppose this can be closed now that commit 066651d was added.