pango: fix pango_default_break function

bug: https://bugzilla.gnome.org/show_bug.cgi?id=785978#c9

(fixes the failing perl-gtk2 tests)

pkgs/development/libraries/pango/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, pkgconfig, libXft, cairo, harfbuzz
+{ stdenv, fetchurl, fetchpatch, pkgconfig, libXft, cairo, harfbuzz
 , libintlOrEmpty, gobjectIntrospection, darwin
 }:
 
@@ -16,6 +16,15 @@ stdenv.mkDerivation rec {
     sha256 = "9faea6535312fe4436b93047cf7a04af544eb52a079179bd3a33821aacce7e16";
   };
 
+  patches = [
+    # https://bugzilla.gnome.org/show_bug.cgi?id=785978#c9
+    (fetchpatch rec {
+      name = "pango-fix-gtk2-test-failures.patch";
+      url = "https://bug785978.bugzilla-attachments.gnome.org/attachment.cgi?id=357690&action=diff&collapsed=&context=patch&format=raw&headers=1";
+      sha256 = "055m2dllfr5pgw6bci72snw38f4hsyw1x7flj188c965ild8lq3a";
+    })
+  ];
+
   outputs = [ "bin" "dev" "out" "devdoc" ];
 
   buildInputs = [ gobjectIntrospection ];