gettext: Check for existence of stdenv.ccCross.

Should only affect cross-builds, however I didn't test whether
cross-building gettext actually works. But if it's broken now, it was
broken before as well and this at least unbreaks the non-cross-built
nixpkgs tarball job :-)

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/development/libraries/gettext/default.nix

@@ -35,7 +35,7 @@ stdenv.mkDerivation (rec {
   enableParallelBuilding = true;
 
   crossAttrs = {
-    buildInputs = stdenv.lib.optional (stdenv.ccCross.libc ? libiconv)
+    buildInputs = stdenv.lib.optional (stdenv ? ccCross && stdenv.ccCross.libc ? libiconv)
       stdenv.ccCross.libc.libiconv.crossDrv;
     # Gettext fails to guess the cross compiler
     configureFlags = "CXX=${stdenv.cross.config}-g++";