Revert "fontconfig: update 2.10.2 -> 2.11.0"

This reverts commit 32a4081.

After ec985c8 the apps linked to 2.11 fontconfig run fine on nixos
with older /etc/fonts/, but the other way won't work.

Unfortunately, I see no easy work-around ATM.

pkgs/development/libraries/fontconfig/default.nix

@@ -1,11 +1,11 @@
 { stdenv, fetchurl, pkgconfig, freetype, expat }:
 
 stdenv.mkDerivation rec {
-  name = "fontconfig-2.11.0";
+  name = "fontconfig-2.10.2";
 
   src = fetchurl {
     url = "http://fontconfig.org/release/${name}.tar.bz2";
-    sha256 = "0rx4q7wcrz4lkpgcmqkwkp49v1fm0yxl0f35jn75dj1vy3v0w3nb";
+    sha256 = "0llraqw86jmw4vzv7inskp3xxm2gc64my08iwq5mzncgfdbfza4f";
   };
 
   infinality_patch = with freetype.infinality; if useInfinality