MMPX texture upscaler not working on macOS/iOS

[hrydgard]

Both hang or freeze for a long time during shader compilation, I guess we hit some bug in the Metal shader compiler?

Just FYI @crashGG

I'm going to blacklist the shader from Apple platforms for now.

Reported by Verymelon on Discord.

[crashGG]

I suspect the Metal shader compiler has low efficiency when dealing with deeply nested conditional branches and complex Boolean logic combinations. Unfortunately, I don’t have an iOS device. Perhaps I can create a lightweight version for iOS that only fixes the visual artifacts present in the original MMPX algorithm.

[hrydgard]

Yeah, although it's surprising because Metal's shader compiler is usually really good!