[compiler-rt] Add flags to dump IR to a file before and after LLVM passes (PR #65179)

[Nuri Amari via llvm-commits]

NuriAmari wrote:

I'm having a bit of a hard time getting the output path tests to pass in CI, while they pass on my Linux machine. I also can't see the output observed in CI, so its a little hard to fix.

I believe the variance comes from the output of this function being unreliable: https://github.com/llvm/llvm-project/blob/208fa9acc0ffe5a460bcd504229c24a8d3f87180/llvm/include/llvm/Support/TypeName.h#L27.

I've loosened the requirements on the paths again in the latest commit, hopefully that satisfies CI while still testing a reasonable amount.

https://github.com/llvm/llvm-project/pull/65179