Change SetStringSelection to return bool like in other classes and ports

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@26990 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/combobox.h

@@ -96,7 +96,7 @@ public:
     int Number() const { return GetCount(); }
     void SetSelection( int n );
     void Select( int n ) { return SetSelection( n ); }
-    void SetStringSelection( const wxString &string );
+    bool SetStringSelection( const wxString &string );
     void SetString(int n, const wxString &text);
 
     wxString GetValue() const;