[librsvg/rustification] Remove unused global variable

[Federico Mena Quintero <federico src gnome org>]

commit 0a416d70c6fcbcff50eb26bbefd0fae1d4de28d0
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Nov 9 14:22:40 2016 -0600

    Remove unused global variable

 rsvg-cairo-draw.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
---
diff --git a/rsvg-cairo-draw.c b/rsvg-cairo-draw.c
index d1352ef..72c8de0 100644
--- a/rsvg-cairo-draw.c
+++ b/rsvg-cairo-draw.c
@@ -41,8 +41,6 @@
 
 #include <pango/pangocairo.h>
 
-static const cairo_user_data_key_t surface_pixel_data_key;
-
 static void
 _pattern_add_rsvg_color_stops (cairo_pattern_t * pattern,
                                GPtrArray * stops, guint32 current_color_rgb, guint8 opacity)