[gtk+] Remove a no-longer existing function

[Matthias Clasen <matthiasc src gnome org>]

commit 883c0d1708ae45d6336b831e3185fb04c74db7cc
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 31 21:59:47 2017 -0400

    Remove a no-longer existing function

 gdk/gdkinternals.h |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
---
diff --git a/gdk/gdkinternals.h b/gdk/gdkinternals.h
index 1a89c0d..20c4def 100644
--- a/gdk/gdkinternals.h
+++ b/gdk/gdkinternals.h
@@ -392,8 +392,6 @@ cairo_region_t *gdk_window_get_current_paint_region (GdkWindow *window);
 void       _gdk_window_process_updates_recurse (GdkWindow *window,
                                                 cairo_region_t *expose_region);
 
-void       _gdk_screen_set_resolution    (GdkScreen      *screen,
-                                          gdouble         dpi);
 void       _gdk_screen_close             (GdkScreen      *screen);
 
 GdkWindow *gdk_get_default_root_window (void);