[llvm] [SPIR-V] Add partial order tests, assert reducible (PR #117887)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

> @Keenuts - I think that the build failures above, that are timeouts, are related to this change. I also see a SPIRVTests.exe process get stuck when I run the tests locally.

Thanks!
There is a test that is expected to hit an assert (otherwise it hangs). Do you build with asserts enabled?
(I might need to replace this assert with another way to die)

https://github.com/llvm/llvm-project/pull/117887