[glibmm] C++11: Gio::*Source: Use the override keyword.

[Murray Cumming <murrayc src gnome org>]

commit a305083346660ec154ea1364d5d8cb894622db3b
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Oct 26 22:23:40 2015 +0100

    C++11: Gio::*Source: Use the override keyword.

 glib/glibmm/main.h |   18 +++++++++---------
 1 files changed, 9 insertions(+), 9 deletions(-)
---
diff --git a/glib/glibmm/main.h b/glib/glibmm/main.h
index 2dd9358..51d7ff9 100644
--- a/glib/glibmm/main.h
+++ b/glib/glibmm/main.h
@@ -821,9 +821,9 @@ protected:
   explicit TimeoutSource(unsigned int interval);
   virtual ~TimeoutSource() noexcept;
 
-  virtual bool prepare(int& timeout);
-  virtual bool check();
-  virtual bool dispatch(sigc::slot_base* slot);
+  bool prepare(int& timeout) override;
+  bool check() override;
+  bool dispatch(sigc::slot_base* slot) override;
 
 private:
   //TODO: Replace with gint64, because TimeVal is deprecated, when we can break ABI.
@@ -845,9 +845,9 @@ protected:
   IdleSource();
   virtual ~IdleSource() noexcept;
 
-  virtual bool prepare(int& timeout);
-  virtual bool check();
-  virtual bool dispatch(sigc::slot_base* slot_data);
+  bool prepare(int& timeout) override;
+  bool check() override;
+  bool dispatch(sigc::slot_base* slot_data) override;
 };
 
 
@@ -873,9 +873,9 @@ protected:
 
   virtual ~IOSource() noexcept;
 
-  virtual bool prepare(int& timeout);
-  virtual bool check();
-  virtual bool dispatch(sigc::slot_base* slot);
+  bool prepare(int& timeout) override;
+  bool check() override;
+  bool dispatch(sigc::slot_base* slot) override;
 
 private:
   PollFD poll_fd_;