### Description <!-- Describe your changes. --> ### Motivation and Context By default, CMAKE_SYSTEM_PROCESSOR is same CMAKE_HOST_SYSTEM_PROCESSOR https://cmake.org/cmake/help/latest/variable/CMAKE_SYSTEM_PROCESSOR.html KleidiAI uses CMAKE_SYSTEM_PROCESSOR to determine whether to include some arm64 ukernels. https://gitlab.arm.com/kleidi/kleidiai/-/blob/main/CMakeLists.txt#L134 We use Mac with Intel CPU to cross compile MAC with ARM in ios packaging pipeline So we need to make CMAKE_SYSTEM_PROCESSOR same with ORT_TARGET_PROCESSOR
