Add AC_PROG_LIBTOOL as autogen.sh will fail otherwise.

diff -ur xf86-video-nouveau-0.0.16_pre20111109-orig/configure.ac xf86-video-nouveau-0.0.16_pre20111109/configure.ac
--- xf86-video-nouveau-0.0.16_pre20111109-orig/configure.ac	2011-11-10 00:13:11.000000000 +0100
+++ xf86-video-nouveau-0.0.16_pre20111109/configure.ac	2012-02-26 15:19:49.000000000 +0100
@@ -49,6 +49,7 @@
 
 # Checks for programs.
 AC_DISABLE_STATIC
+AC_PROG_LIBTOOL
 LT_INIT
 AC_PROG_CC