* Allow .so dynamic libraries on Darwin This code is a hack that applied only to Darwin, it collects all required dynamic libraries into a single directory. It does this by listing all library dirs and then linkin all dynamic libraries in them. Before this change, it would link only `*.dylib` files. This was a problem, because (weirdly) a lot of libraries in Nixpkgs actually produce .so even on Darwin (and, weirdly, this somehow works). So we now link `.so` files as well. * Fix linking of dynamic libs with static on Darwin This piece of code `ln`s all libraries we might want to link with into a single directory and then hides all previous directories from Cabal. The problem is that this code only `ln`s dynamic libraries, however we might want to link with some library that only comes in a static version. So, `ln` static `.a` libraries too so that they are found when linking.