[llvm] [update_mc_test_checks] Fix llvm-mc invocation on Windows by avoiding echo pipe (PR #179381)

[Harrison Hao via llvm-commits]

harrisonGPU wrote:

> > Even if I set this flag to false, it still fails on Windows. The root cause is that cmd.exe’s echo preserves quotes, so the input line is passed with literal " and llvm-mc parses it incorrectly.
> 
> Given that, it seems like this change wouldn't be super useful in it's current form given the output will differ by platform. If we want to make this actually work on Windows, I think Alexander's suggestion of trying to reuse some of the lit builtins is a good idea if there is no other easy way to make this work.

Thanks, but I believe this patch already supports both Windows and Linux, echo isn't required as input.

https://github.com/llvm/llvm-project/pull/179381