[llvm] [FileCheck] Use default colors in input dumps (PR #204936)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> I never found a nice way to write tests checking that FileCheck emits expected color codes.

`lld/test/ELF/color-diagnostics.test` has an example to test ANSI escape sequences, but Windows should be unsupported.

https://github.com/llvm/llvm-project/pull/204936