[libxml2] Remove git error message during configure

[Daniel Veillard <veillard src gnome org>]

commit 040dcb5995f5622e8a82b93fdffc2f919e7e6dc4
Author: Christian Dywan <christian twotoasts de>
Date:   Thu May 10 22:55:07 2012 +0800

    Remove git error message during configure
    
    For https://bugzilla.gnome.org/show_bug.cgi?id=635531
    If git is not installed but .git was found configure would emit an
    error message

 configure.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.in b/configure.in
index 38552a7..ada25cd 100644
--- a/configure.in
+++ b/configure.in
@@ -29,7 +29,7 @@ else if test -d .svn ; then
       LIBXML_VERSION_EXTRA="-SVN$extra"
   fi
 else if test -d .git ; then
-  extra=`git describe | sed 's+LIBXML[[0-9.]]*-++'`
+  extra=`git describe 2>/dev/null | sed 's+LIBXML[[0-9.]]*-++'`
   echo extra=$extra
   if test "$extra" != ""
   then