[llvm] [LTOBackend] Add -filter-save-modules= for save-temps to only dump specific modules. (PR #175696)

[Teresa Johnson via llvm-commits]

https://github.com/teresajohnson approved this pull request.

lgtm with one minor suggestion on the test below.

Also, for future PRs, note that you should avoid force pushes while they are still under review if possible. See https://llvm.org/docs/GitHub.html#rebasing-pull-requests-and-force-pushes.

https://github.com/llvm/llvm-project/pull/175696