[llvm] Make update_any_test_check.py script accepting @listfile CL argument. (PR #86800)

[Tobias Hieta via llvm-commits]

tru wrote:

> Is their precedent somewhere for using the '@' as a prefix in this way? Seems a bit unorthodox to me.

This is handled by lld and clang as well. It's called response files there and is usually a way to work around issues with command line length. 

https://github.com/llvm/llvm-project/pull/86800