added missing setter function on create_torrent

src/create_torrent.cpp

@@ -492,6 +492,11 @@ namespace libtorrent
 		m_comment = str;
 	}
 
+	void create_torrent::set_encryption_key(std::string const& key)
+	{
+		m_encryption_key = key;
+	}
+
 	void create_torrent::set_creator(char const* str)
 	{
 		m_created_by = str;