Rollup merge of rust-lang#102587 - Enselic:rustc-unix_sigpipe, r=jack…

…h726

rustc: Use `unix_sigpipe` instead of `rustc_driver::set_sigpipe_handler`

This is the first (known) step towards starting to use `unix_sigpipe` in the wild. Eventually, `rustc_driver::set_sigpipe_handler` can be removed and all clients can use `unix_sigpipe` instead.

For now we just start using `unix_sigpipe` in one place: `rustc` itself.

It is easy to manually verify this change. If you remove `#[unix_sigpipe = "sig_dfl"]` and run `./x.py build` you will get an ICE when you do `./build/x86_64-unknown-linux-gnu/stage1/bin/rustc --help | false`. Add back `#[unix_sigpipe = "sig_dfl"]` and the ICE disappears again.

PR that added `set_sigpipe_handler`: rust-lang#49606

Tracking issue for `unix_sigpipe`: rust-lang#97889

Not sure exactly how to label this PR. Going with T-libs for now since this is a T-libs feature.

````@rustdoc```` labels +T-libs