Don't handle special case of reductions for scalar inputs and "empty" reduction axes

TFlite has a wierd thing where it allows specifying that the shape `{0}` (not `{}`) means "scalar" or empty. XNNPACK does not have this special case, and I don't think we should support it.

PiperOrigin-RevId: 882225739

Author: dsharletg

tflite/delegates/xnnpack/xnnpack_delegate.cc

@@ -4918,7 +4918,9 @@ class Subgraph {
     const int32_t* axes_data =
         reinterpret_cast<const int32_t*>(axes_tensor.data.data);
     const int num_reduction_axes = NumElements(&axes_tensor);
-    if (num_reduction_axes <= 0) {
+    if (num_reduction_axes <= 0 ||
+        (num_reduction_axes == 1 && axes_data[0] == 0 &&
+         input_tensor.dims->size == 0)) {
       TF_LITE_MAYBE_KERNEL_LOG(
           logging_context,
           "Not handling ill defined empty reduction in node #%d", node_index);