[gtkmm] Add necessary #include<>s

[Kjell Ahlstedt <kjellahl src gnome org>]

commit bd32fdfc74dacfe3556039c11b23ba4e9218282b
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Fri Oct 26 21:54:06 2018 +0200

    Add necessary #include<>s
    
    * gdk/src/contentprovider.hg
    * gtk/src/papersize.hg

 gdk/src/contentprovider.hg | 2 ++
 gtk/src/papersize.hg       | 1 +
 2 files changed, 3 insertions(+)
---
diff --git a/gdk/src/contentprovider.hg b/gdk/src/contentprovider.hg
index b758ad2e..d3213ab0 100644
--- a/gdk/src/contentprovider.hg
+++ b/gdk/src/contentprovider.hg
@@ -17,6 +17,8 @@
 _DEFS(gdkmm,gdk)
 _PINCLUDE(glibmm/private/object_p.h)
 
+#include <glibmm/bytes.h>
+#include <glibmm/object.h>
 #include <glibmm/refptr.h>
 #include <gdkmm/contentformats.h>
 
diff --git a/gtk/src/papersize.hg b/gtk/src/papersize.hg
index 991d9fbe..69ee4ce1 100644
--- a/gtk/src/papersize.hg
+++ b/gtk/src/papersize.hg
@@ -18,6 +18,7 @@
 _DEFS(gtkmm,gtk)
 
 #include <glibmm/keyfile.h>
+#include <glibmm/value.h>
 #include <vector>
 
 namespace Gtk