[glibmm] Examples: OptionGroup: Make the args public again to fix the build.

[Murray Cumming <murrayc src gnome org>]

commit e1dba38d6b9a6d08c6ddb868a9dae825f4c10932
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Jul 15 13:22:10 2015 +0200

    Examples: OptionGroup: Make the args public again to fix the build.

 examples/options/main.cc |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/examples/options/main.cc b/examples/options/main.cc
index d693d09..fcda4a9 100644
--- a/examples/options/main.cc
+++ b/examples/options/main.cc
@@ -35,6 +35,7 @@ private:
   bool on_option_arg_filename(const Glib::ustring& option_name,
     const std::string& value, bool has_value);
 
+public:
   //These members should live as long as the OptionGroup to which they are added, 
   //and as long as the OptionContext to which that OptionGroup is added.
   int m_arg_foo;