[libxml2] Downgrade autoconf requirement to 2.63

[Daniel Veillard <veillard src gnome org>]

commit 5d04ad11a8adb38537dc8ceb69416c0f6ca2b1b8
Author: Daniel Veillard <veillard redhat com>
Date:   Tue Sep 11 17:17:15 2012 +0800

    Downgrade autoconf requirement to 2.63
    
    It was automatically bumped to 2.68 and that's not needed

 configure.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.in b/configure.in
index 3d5f48b..6da057c 100644
--- a/configure.in
+++ b/configure.in
@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-AC_PREREQ([2.68])
+AC_PREREQ([2.63])
 AC_INIT
 AC_CONFIG_SRCDIR([entities.c])
 AC_CONFIG_HEADERS([config.h])