Implement array_entry_t copy constructor

Manually initialize the array_entry_t iterator to ensure it points
to the correct m_array, thereby preventing a potential use-after-free
situation.

Signed-off-by: Guido Vranken <guidovranken@gmail.com>

contrib/epee/include/storages/portable_storage_base.h

@@ -82,6 +82,7 @@ namespace epee
     struct array_entry_t
     {
       array_entry_t():m_it(m_array.end()){}        
+      array_entry_t(const array_entry_t& other):m_array(other.m_array), m_it(m_array.end()){}
 
       const t_entry_type* get_first_val() const 
       {