Properly annotate variable-length output parameters.  Make sure that the
client-side code doesn't try to calculate the size of the output
parameters.  The server will tell the client how big it is.
diff --git a/src/mesa/glapi/glX_XML.py b/src/mesa/glapi/glX_XML.py
index 6eb2f55..1db12f5 100644
--- a/src/mesa/glapi/glX_XML.py
+++ b/src/mesa/glapi/glX_XML.py
@@ -452,6 +452,14 @@
 		return None
 
 
+	def output_parameter(self):
+		for param in self.fn_parameters:
+			if param.is_output:
+				return param
+
+		return None
+
+
 	def offset_of_first_parameter(self):
 		"""Get the offset of the first parameter in the command.