More border rationalisation. GetDefaultBorder is now mostly defined in base class files.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49893 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/univ/tglbtn.h

@@ -57,6 +57,8 @@ public:
     bool GetValue() const { return m_value; }
 
 protected:
+    virtual wxBorder GetDefaultBorder() const { return wxBORDER_NONE; }
+
     // the current value
     bool m_value;