Return early if render resources already deallocated

[jcavar]

This fixes the crash in macOS and iOS 26. This is the same fix @NickCulbertson did in his branch, just without manual flag management.

It seems like the engine should perform this check internally and not invoke deallocateRenderResources when not needed, but this also feels like low risk change to protect against buggy host.

Resolves: https://github.com/AudioKit/AudioKitEX/issues/33