IVGCVSW-4246 Clean build of backends with -Wextra

Change-Id: I9e8d5576b3ec04c871785d5f2f9545bf1136e59b
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/backends/backendsCommon/test/TestDynamicBackend.cpp b/src/backends/backendsCommon/test/TestDynamicBackend.cpp
index a53f169..cbfe093 100644
--- a/src/backends/backendsCommon/test/TestDynamicBackend.cpp
+++ b/src/backends/backendsCommon/test/TestDynamicBackend.cpp
@@ -7,6 +7,8 @@
 
 #include <armnn/backends/IBackendInternal.hpp>
 
+#include <boost/core/ignore_unused.hpp>
+
 constexpr const char* TestDynamicBackendId()
 {
 #if defined(VALID_TEST_DYNAMIC_BACKEND_1)
@@ -63,6 +65,7 @@
     }
     IWorkloadFactoryPtr CreateWorkloadFactory(const IMemoryManagerSharedPtr& memoryManager) const override
     {
+        boost::ignore_unused(memoryManager);
         return IWorkloadFactoryPtr{};
     }
     ILayerSupportSharedPtr GetLayerSupport() const override