[gtksourceviewmm] Gutter: Remove include of gdkmm/window.h

[Murray Cumming <murrayc src gnome org>]

commit 160b2d533ec33badf449a8c0222f9b6db206fc64
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Sep 27 22:58:44 2019 +0200

    Gutter: Remove include of gdkmm/window.h
    
    Because it has been renamed to gdkmm/surface.h and doesn't seem to be
    needed anyway.

 gtksourceview/src/gutter.hg | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/gtksourceview/src/gutter.hg b/gtksourceview/src/gutter.hg
index df0a560..501cda4 100644
--- a/gtksourceview/src/gutter.hg
+++ b/gtksourceview/src/gutter.hg
@@ -20,7 +20,6 @@
 /// \file
 /// \brief Gutter class
 
-#include <gdkmm/window.h>
 #include <glibmm/object.h>
 #include <glibmm/refptr.h>
 #include <gtksourceviewmm/gutterrenderer.h>