I wish there was a nicer way to do this, but SystemSupportedProcessorArchitectures is incomplete on ARM64EC even on Windows so there isn't really a cleaner way I can find.
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v3: msi: Dynamically determine supported package architectures.
msi: Assume PLATFORM_INTEL if the template property is missing.
https://gitlab.winehq.org/wine/wine/-/merge_requests/6838