[gtk+] Drop some no-longer existing headers

[Matthias Clasen <matthiasc src gnome org>]

commit 0d8444d067e1b480766561cbe85cfb36bd308c54
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 27 20:11:00 2015 -0400

    Drop some no-longer existing headers

 gtk/Makefile.am |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
---
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 7d2ebdf..ca42f8e 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -508,11 +508,9 @@ gtk_private_h_sources =            \
        gtksearchenginemodel.h  \
        gtksearchentryprivate.h \
        gtkselectionprivate.h   \
-       gtksidebarrowprivate.h  \
        gtksettingsprivate.h    \
-       gtkshortcutsgestureprivate.h    \
        gtkshortcutlabelprivate.h       \
-       gtkshortcutsshortcutprivate.h   \
+       gtksidebarrowprivate.h  \
        gtksizegroup-private.h  \
        gtksizerequestcacheprivate.h    \
        gtksocketprivate.h      \