[gtkglarea] configure.ac: Use new modern libtool syntax

[Javier Jardón <jjardon src gnome org>]

commit 3a176dcc99eab107d8f1c0855c53b8a2e9a7fb54
Author: Javier Jardón <jjardon gnome org>
Date:   Thu Feb 27 02:22:08 2014 +0000

    configure.ac: Use new modern libtool syntax

 configure.ac |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index cfc62fc..de9e534 100644
--- a/configure.ac
+++ b/configure.ac
@@ -29,8 +29,10 @@ AC_SUBST(VERSION)
 dnl Checks for programs.
 AC_PROG_CC
 AC_PROG_CPP
-AC_LIBTOOL_WIN32_DLL
-AM_PROG_LIBTOOL
+
+dnl Initialize libtool
+LT_PREREQ([2.2.6])
+LT_INIT([win32-dll])
 AM_SANITY_CHECK
 
 dnl