[gtksourceview] gutterrenderermarks: free composited pixbuf

[Christian Hergert <chergert src gnome org>]

commit 7137a02ca221bcc2f1262125b2fe578d45bf37b8
Author: Christian Hergert <chergert redhat com>
Date:   Tue Feb 19 11:46:04 2019 -0800

    gutterrenderermarks: free composited pixbuf
    
    This fixes a leak of the composited pixbuf that is generated using the
    source marks within the buffer.
    
    Related to #39

 gtksourceview/gtksourcegutterrenderermarks.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtksourceview/gtksourcegutterrenderermarks.c b/gtksourceview/gtksourcegutterrenderermarks.c
index 04950fa7..8978b313 100644
--- a/gtksourceview/gtksourcegutterrenderermarks.c
+++ b/gtksourceview/gtksourcegutterrenderermarks.c
@@ -199,6 +199,8 @@ gutter_renderer_query_data (GtkSourceGutterRenderer      *renderer,
                      "xalign", 0.5,
                      "alignment-mode", GTK_SOURCE_GUTTER_RENDERER_ALIGNMENT_MODE_FIRST,
                      NULL);
+
+       g_clear_object (&pixbuf);
 }
 
 static gboolean