IVGCVSW-4246 Clean build of Visitors with -Wextra

Change-Id: Icb1b35ff55fa22103777853e6f49fc282d61750d
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/armnnDeserializer/test/DeserializeAdd.cpp b/src/armnnDeserializer/test/DeserializeAdd.cpp
index b053b10..be292bc 100644
--- a/src/armnnDeserializer/test/DeserializeAdd.cpp
+++ b/src/armnnDeserializer/test/DeserializeAdd.cpp
@@ -7,6 +7,8 @@
 #include "ParserFlatbuffersSerializeFixture.hpp"
 #include "../Deserializer.hpp"
 
+#include <boost/core/ignore_unused.hpp>
+
 #include <string>
 #include <iostream>
 
@@ -20,6 +22,7 @@
                         const std::string & dataType,
                         const std::string & activation="NONE")
     {
+        boost::ignore_unused(activation);
         m_JsonString = R"(
         {
                 inputIds: [0, 1],