Insert, not append explicit xcbgen dir python path

If a the path to the xcb python generate libs is
explicitly specified to c_client.py, insert it in
the python path list just after the local dir entry,
rather than appending it to the existing paths.
This keeps a global/distro install of xcb from
overriding a local build of the xcb proto files.

Signed-off-by: James Jones <jajones@nvidia.com>
Signed-off-by: Jamey Sharp <jamey@minilop.net>

src/c_client.py

@@ -2290,7 +2290,7 @@ except getopt.GetoptError as err:
 
 for (opt, arg) in opts:
     if opt == '-p':
-        sys.path.append(arg)
+        sys.path.insert(1, arg)
 
 # Import the module class
 try: