Enabling wscript-based configuration

Change-Id: Idb70b2bfe17ad61fc37bfe839ae3b9c6ac98c8e6
diff --git a/wscript b/wscript
index 1fe7a68..03fb3cf 100644
--- a/wscript
+++ b/wscript
@@ -50,6 +50,8 @@
         conf.load('sparkle')
     else:
         conf.load('qt4')
+        conf.find_program('xsltproc', mandatory=True)
+        conf.define('XSLTPROC', conf.env['XSLTPROC'])
         
         if Utils.unversioned_sys_platform () == "darwin":
             conf.define('OSX_BUILD', 1)