Start using `unix_sigpipe` instead of
`rustc_driver::set_sigpipe_handler`.
After this has been merged, we can completely remove
`rustc_driver::set_sigpipe_handler`.
Verification of this change
---------------------------
1. Remove `#[unix_sigpipe = "sig_dfl"]`
1. Run `./x.py build`
1. Run `./build/aarch64-apple-darwin/stage1/bin/rustdoc --help | false`
1. Observe ICE
1. Add back `#[unix_sigpipe = "sig_dfl"]`
1. Run `./x.py build`
1. Run `./build/aarch64-apple-darwin/stage1/bin/rustdoc --help | false`
1. Observe ICE fixed
Since RFC 3052 soft deprecated the authors field anyway, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information, we should remove it from
crates in this repo.
