Tecgraf libraries (IUP, CD and IM) as Common Lisp ASDF System

This system includes a shell script, update.sh which downloads the Tecgraf shared libraries for Windows and Linux and places them in subdirectory libs/. See also https://www.tecgraf.puc-rio.br/iup/en/download_tips.html

The shared libraries are then included in this repository.
The location of the shared libraries can be referenced from (asdf:system-relative-pathname "tecgraf-libs" "libs/").
On Linux, patchelf is used set the shared library rpath to $ORIGIN so that the interdependencies between the Tecgraf shared libraries can be found relative to each other.