[llvm] [SPIRV] Change how to detect OpenCL/Vulkan Env and update tests accordingly. (PR #129689)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts approved this pull request.

I think this is OK for me, as I don't think there are any other target than OpenCL/Vulkan for now. This can be revisited when Microsoft adds their DX/SPIRV thing

https://github.com/llvm/llvm-project/pull/129689