MLCE-328 Serializer/Deserializer does not support Signed64

 * Added support for Signed64 to flatbuffer's schema & updated source tree
 * Added support for Signed64 to TFLite Delegate
 * Added support for Signed64 to Serializer
 * Added support for Signed64 to Deserializer
 * Added unit test for ArgMinMax to Deserializer
 * Deprecated m_Output_Type from the ArgMinMaxDescriptor: the output type
   is solely determined by the DataType of the output Tensor
 * Fixed issue where RefArgMinMaxWorkload could output data using
   the wrong DataType
 * Added Signed64 to RefLayerSupport::IsArgMinMaxSupported as a supported
   type

Signed-off-by: Mike Kelly <mike.kelly@arm.com>
Signed-off-by: Matthew Sloyan <matthew.sloyan@arm.com>
Change-Id: Ib622c052a1f8aa3e658262f8bde5a6881a8cbe10
diff --git a/src/armnnSerializer/Serializer.cpp b/src/armnnSerializer/Serializer.cpp
index ae9ddf2..15ae78c 100644
--- a/src/armnnSerializer/Serializer.cpp
+++ b/src/armnnSerializer/Serializer.cpp
@@ -1718,6 +1718,15 @@
 
     switch (tensorInfo.GetDataType())
     {
+        case armnn::DataType::Signed64:
+        {
+            auto fbVector = CreateDataVector<int64_t>(constTensor.GetMemoryArea(), constTensor.GetNumBytes());
+            flatbuffers::Offset<serializer::LongData> flatBuffersData = serializer::CreateLongData(
+                    m_flatBufferBuilder,
+                    fbVector);
+            fbPayload = flatBuffersData.o;
+            break;
+        }
         case armnn::DataType::Float32:
         case armnn::DataType::Signed32:
         {