[gtksourceview] GutterRenderer: fix includes (implicit declarations)

[Sébastien Wilmet <swilmet src gnome org>]

commit 7c22af08fa0ef62c75e2c8ff97cad9c7fb05a320
Author: Martin Blanchard <martin blanchard codethink co uk>
Date:   Mon Feb 26 14:27:26 2018 +0000

    GutterRenderer: fix includes (implicit declarations)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=793842

 gtksourceview/gtksourcegutterrenderer.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtksourceview/gtksourcegutterrenderer.c b/gtksourceview/gtksourcegutterrenderer.c
index b9c52dd..daa1a9f 100644
--- a/gtksourceview/gtksourcegutterrenderer.c
+++ b/gtksourceview/gtksourcegutterrenderer.c
@@ -25,6 +25,7 @@
 #include "gtksourcegutterrenderer.h"
 #include "gtksourcegutterrenderer-private.h"
 #include "gtksourcestylescheme.h"
+#include "gtksourceview.h"
 #include "gtksource-enumtypes.h"
 
 /**