IVGCVSW-4246 Clean build of LayerTests with -Wextra

Change-Id: If3d98e45a6e2fa8e1afd19a4052334335feacf63
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
diff --git a/src/backends/backendsCommon/test/layerTests/ComparisonTestImpl.cpp b/src/backends/backendsCommon/test/layerTests/ComparisonTestImpl.cpp
index 1c54b85..c8272f4 100644
--- a/src/backends/backendsCommon/test/layerTests/ComparisonTestImpl.cpp
+++ b/src/backends/backendsCommon/test/layerTests/ComparisonTestImpl.cpp
@@ -44,6 +44,7 @@
     float outQuantScale,
     int outQuantOffset)
 {
+    boost::ignore_unused(memoryManager);
     BOOST_ASSERT(shape0.GetNumDimensions() == NumDims);
     armnn::TensorInfo inputTensorInfo0(shape0, ArmnnInType, quantScale0, quantOffset0);