check nchwc_inputs before accessing

[s0md3v]

Description

Fixes a build error by checking that nchwc_inputs is not empty before accessing its elements in TransformBinary.

Motivation and Context

Compiler flagged a possible uninitialized access to nchwc_inputs[0] (when empty), causing the build to fail. This check ensures safe access and avoids undefined behavior. No impact on valid graphs.

[tianleiwu]

/azp run Linux QNN CI Pipeline,Win_TRT_Minimal_CUDA_Test_CI,Windows ARM64 QNN CI Pipeline,Windows GPU Doc Gen CI Pipeline,Windows x64 QNN CI Pipeline

[azure-pipelines]

Azure Pipelines successfully started running 5 pipeline(s).

[tianleiwu]

It is false alert since the function is applied to Add, Sum, Mul which shall have at least two inputs.

onnxruntime/onnxruntime/core/optimizer/nchwc_transformer.cc

Lines 1164 to 1168 in c122f0d

	if (graph_utils::IsSupportedOptypeVersionAndDomain(node, "Add", {7, 13, 14}) ||
	graph_utils::IsSupportedOptypeVersionAndDomain(node, "Sum", {6, 8, 13})) {
	TransformBinary(node, true);
	} else if (graph_utils::IsSupportedOptypeVersionAndDomain(node, "Mul", {7, 13, 14})) {
	TransformBinary(node, false);

Anyway, an extra check is fine to me even though not necessary.