[glibmm/mkolny/meson-build] Apply masters fix

[Marcin Kolny <mkolny src gnome org>]

commit 5cb89319c03e381b6d1791f5c570bed475e24c7a
Author: Marcin Kolny <marcin kolny gmail com>
Date:   Wed Aug 2 21:06:01 2017 +0100

    Apply masters fix

 glib/glibmm/object.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/glib/glibmm/object.h b/glib/glibmm/object.h
index d55db05..2a2eb78 100644
--- a/glib/glibmm/object.h
+++ b/glib/glibmm/object.h
@@ -237,7 +237,7 @@ template <class PtrT>
 inline PtrT
 Value_Pointer<PtrT>::get_(Glib::Object*) const
 {
-  return dynamic_cast<PtrT>(get_object());
+  return dynamic_cast<T>(get_object());
 }
 
 /** Partial specialization for RefPtr<> to Glib::Object.