[gitg] Added libxml2 dependency for osx

[Jesse van den Kieboom <jessevdk src gnome org>]

commit ba2c8bebe858e87060839f5ed4d13ec80eae7fa8
Author: Jesse van den Kieboom <jessevdk gnome org>
Date:   Sun Jan 31 10:54:13 2016 +0100

    Added libxml2 dependency for osx

 osx/Taps/gitg/gitg.rb |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/osx/Taps/gitg/gitg.rb b/osx/Taps/gitg/gitg.rb
index 2227d37..67ce94f 100644
--- a/osx/Taps/gitg/gitg.rb
+++ b/osx/Taps/gitg/gitg.rb
@@ -22,6 +22,7 @@ class Gitg < Formula
   depends_on "gnome/gitg/gsettings-desktop-schemas"
   depends_on "gnome/gitg/libgit2-glib" => "with-vala"
   depends_on "gnome/gitg/gnome-icon-theme"
+  depends_on "libxml2"
 
   def install
     system "./autogen.sh", "--disable-dependency-tracking",