Double link inner-outer methods

This allows inner methods to access method_defrag to get negotiated
EAP-TTLS/PEAP protocol version.

Signed-off-by: Simon Rozman <simon@rozman.si>

lib/EAPBase/include/Method.h

@@ -192,6 +192,7 @@ namespace eap
 
     public:
         module &m_module;   ///< Module for global services
+        method *m_outer;    ///< Outer method
     };