Sync from tflite-micro. (tensorflow#171)

Author: TFLM-bot

src/tensorflow/lite/core/c/common.cpp

@@ -346,7 +346,7 @@ void* TfLiteOpaqueDelegateGetData(const TfLiteOpaqueDelegate* delegate) {
   const auto* tflite_delegate =
       reinterpret_cast<const TfLiteDelegate*>(delegate);
 
-  if (!tflite_delegate->opaque_delegate_builder) return nullptr;
+  if (!tflite_delegate->opaque_delegate_builder) return tflite_delegate->data_;
 
   return tflite_delegate->opaque_delegate_builder->data;
 }

src/tensorflow/lite/core/c/common.h

@@ -1148,6 +1148,9 @@ void TfLiteOpaqueDelegateDelete(TfLiteOpaqueDelegate* delegate);
 // - Or in case of any other error.
 // - The 'delegate' has been constructed via a 'TfLiteOpaqueDelegateBuilder',
 //   but the 'data' field of the 'TfLiteOpaqueDelegateBuilder' is null.
+//
+//  The data_ field of 'delegate' will be returned if the
+//  'opaque_delegate_builder' field is null.
 void* TfLiteOpaqueDelegateGetData(const TfLiteOpaqueDelegate* delegate);
 
 #ifdef __cplusplus