Minor refactoring and code tweaking.  The only notable chage is that
FilterGLAPISpecBase::xref is replaced by
FilterGLAPISpecBase::functions_by_name.  The notable difference between the
two is that ::functions_by_name includes all functions, whether they have an
assigned offset or not.  This feature will be useful (necessary) when more
server-side code is generated.
diff --git a/src/mesa/glapi/glX_XML.py b/src/mesa/glapi/glX_XML.py
index 3f6f841..98be996 100644
--- a/src/mesa/glapi/glX_XML.py
+++ b/src/mesa/glapi/glX_XML.py
@@ -416,10 +416,9 @@
 
 
 	def variable_length_parameter(self):
-		for param in self.fn_parameters:
-			if param.is_variable_length_array():
-				return param
-			
+		if len(self.variable_length_parameters):
+			return self.variable_length_parameters[0]
+
 		return None