[gtk+] Remove GtkBoxGadget

[Matthias Clasen <matthiasc src gnome org>]

commit 0bab8b8e0e2b0a265f9874ac84ad94a0ea51d83e
Author: Timm Bäder <mail baedert org>
Date:   Wed May 17 18:05:22 2017 +0200

    Remove GtkBoxGadget
    
    Now unused

 gtk/Makefile.am           |    2 -
 gtk/gtkboxgadget.c        |  864 ---------------------------------------------
 gtk/gtkboxgadgetprivate.h |  102 ------
 gtk/meson.build           |    1 -
 4 files changed, 0 insertions(+), 969 deletions(-)
---
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 408edde..bfeafac 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -374,7 +374,6 @@ gtk_private_h_sources =             \
        gtkbitmaskprivateimpl.h \
        gtkbookmarksmanager.h   \
        gtkboxprivate.h         \
-       gtkboxgadgetprivate.h   \
        gtkbuilderprivate.h     \
        gtkbuttonprivate.h      \
        gtkcellareaboxcontextprivate.h  \
@@ -621,7 +620,6 @@ gtk_base_c_sources =                \
        gtkbookmarksmanager.c   \
        gtkborder.c             \
        gtkbox.c                \
-       gtkboxgadget.c          \
        gtkbuildable.c          \
        gtkbuilder.c            \
        gtkbuilderparser.c      \
diff --git a/gtk/meson.build b/gtk/meson.build
index 8785394..dbc8b88 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -35,7 +35,6 @@ gtk_public_sources = files([
   'gtkbookmarksmanager.c',
   'gtkborder.c',
   'gtkbox.c',
-  'gtkboxgadget.c',
   'gtkbuildable.c',
   'gtkbuilder-menus.c',
   'gtkbuilder.c',