stdenv: Pass rewriteURL to freebsd and native stdenvs

Was missing from abda866f17

While the native stdenv's eval seems to be broken anyways,
the freebsd one at least evaluates again with this

pkgs/stdenv/native/default.nix

@@ -192,6 +192,7 @@ in
         inherit lib stdenvNoCC;
         # Curl should be in /usr/bin or so.
         curl = null;
+        inherit (config) rewriteURL;
       };
 
     }