[llvm] [SPIR-V] Add SPIRV to LLVM_ALL_TARGETS (reapply) (PR #123733)

[Vyacheslav Levytskyy via llvm-commits]

VyacheslavLevytskyy wrote:

> Something not working correctly on 32-bit hosts?

Not that we know about.
The reason for a test to fail is in the log: "Invalid optimization level!", suggesting that `CodeGenOpt::parseLevel(...)` returns `std::nullopt`. There is certain weirdness in this, and we are on it.

https://github.com/llvm/llvm-project/pull/123733