ldns: get rid of reference to openssl.dev

Reduces size from ~100MB to ~40M.

pkgs/development/libraries/ldns/default.nix

···
     make
     make install
     popd
+
+    sed -i "$out/lib/libldns.la" -e "s,-L${openssl.dev},-L${openssl.out},g"
   '';
 
   meta = with stdenv.lib; {