various packages fixed

pkgs/development/libraries/libffi/default.nix

@@ -24,8 +24,14 @@ stdenv.mkDerivation rec {
   dontStrip = stdenv ? cross; # Don't run the native `strip' when cross-compiling.
 
   postInstall =
-    # Install headers in the right place.
-    '' ln -s${if stdenv.isFreeBSD then "" else "r"}v "$out/lib/"libffi*/include "$out/include"
+    # Install headers and libs in the right places.
+    ''  mv "$out"/lib64/* "$out/lib"
+        rmdir "$out/lib64"
+        ln -s lib "$out/lib64"
+
+        mkdir -p "$dev/"
+        mv "$out/lib/${name}/include" "$dev/include"
+        rmdir "$out/lib/${name}"
     '';
 
   meta = {