The change 40ced5b enables viewport support based on the toolchain used.

This is not ideal because the device type is not necessarily tied to the toolchain (even for Android and OHOS - what about TVs for instance?). This patch disabled viewport on the Pinephone builds which are using a aarch64-unknown-linux-gnu target.

I think we need a more flexible mechanism to enable or disable support. Maybe an override with a feature flag?