hspell: Add zlib

As mentioned by the configure script output, hspell will fall back
on using `gzip` program when not linked against `zlib`:

    No Zlib library, defaulting to using pipes

It has been removed in 67f0a21 for some reason.

I am getting the following in the journal from `geary` through `enchant`,
hopefully this fixes it:

    Hspell: can't run gzip -dc '/nix/store/14qk9r9ywvpqn0a24fvw1iwjv302d04j-hspell-1.4/share/hspell/hebrew.wgz.prefixes'.

pkgs/development/libraries/hspell/default.nix

@@ -41,7 +41,10 @@ stdenv.mkDerivation rec {
     perl
     zlib
   ];
-  buildInputs = [ perl ];
+  buildInputs = [
+    perl
+    zlib
+  ];
 
   strictDeps = true;