[pitivi] Fix compilation with pycairo 1.17.x

[Thibault Saunier <tsaunier src gnome org>]

commit 0f3e399e387e64dcc3c5015a8aacb26fbe49800f
Author: Eli Schwartz <eschwartz archlinux org>
Date:   Wed Jul 25 13:49:40 2018 -0400

    Fix compilation with pycairo 1.17.x
    
    Do not redefine a thing which was always defined in the included header,
    since that breaks when upstream changes how they do things.
    
    This is a holdover from the initial python2 version, since pycairo
    dropped the use of downstream definition of Pycairo_CAPI during the
    python3 port: https://github.com/pygobject/pycairo/commit/727470e8a170bf355c9689826bb1db95f7c1389e
    
    See https://github.com/pygobject/pycairo/commit/921541295439f812ac51a6cc6d8143a8f10814b4
    for the upstream change that broke this misuse.

 pitivi/coptimizations/renderer.c | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/pitivi/coptimizations/renderer.c b/pitivi/coptimizations/renderer.c
index c655ca5c..2f939412 100644
--- a/pitivi/coptimizations/renderer.c
+++ b/pitivi/coptimizations/renderer.c
@@ -4,7 +4,6 @@
 #include <py3cairo.h>
 #include <gst/gst.h>
 
-static Pycairo_CAPI_t *Pycairo_CAPI;
 static GObjectClass * gobject_class;
 
 /*