#8 Fix the build with slibtool

[orbea]

When building libggi on gentoo both -lncurses and -ltinfo are needed when the build only has the former. Additionally when building libggi with slibtool instead of GNU libtool the build will fail with undefined references for libtinfo because of the -no-undefined. GNU libtool hides this problem by silently ignoring -no-undefined while slibtool does not do this.

Gentoo bug: https://bugs.gentoo.org/775584