cups: split the $lib output

This saves > 10 MB from most closures.
Printing test succeeds on x86_64-linux.

pkgs/misc/cups/drivers/samsung/4.00.39/default.nix

@@ -16,7 +16,7 @@
 # Do not bump lightly! Visit <http://www.bchemnet.com/suldr/supported.html>
 # to see what will break when upgrading. Consider a new versioned attribute.
 let
-  cups' = cups.out;
+  cups' = stdenv.lib.getLib cups;
 in stdenv.mkDerivation rec {
   name = "samsung-UnifiedLinuxDriver-${version}";
   version = "4.00.39";

pkgs/misc/cups/drivers/samsung/default.nix

@@ -72,10 +72,10 @@ in stdenv.mkDerivation rec {
 
   for bin in $out/bin/*; do
     patchelf --set-interpreter "$(cat $NIX_CC/nix-support/dynamic-linker)" "$bin"
-    patchelf --set-rpath "$out/lib:${cups.out}/lib" "$bin"
+    patchelf --set-rpath "$out/lib:${stdenv.lib.getLib cups}/lib" "$bin"
   done
 
-  patchelf --set-rpath "$out/lib:${cups.out}/lib" "$out/lib/libscmssc.so"
+  patchelf --set-rpath "$out/lib:${stdenv.lib.getLib cups}/lib" "$out/lib/libscmssc.so"
 
   ln -s ${stdenv.cc.cc.lib}/lib/libstdc++.so.6 $out/lib/