In the stabilization attempt of `#[unix_sigpipe = "sig_dfl"]`, a concern
was raised related to using a language attribute for the feature: Long
term, we want `fn lang_start()` to be definable by any crate, not just
libstd. Having a special language attribute in that case becomes
awkward.
So as a first step towards towards the next stabilization attempt, this
PR changes the `#[unix_sigpipe = "..."]` attribute to a compiler flag
`-Zon-broken-pipe=...` to remove that concern, since now the language
is not "contaminated" by this feature.
Another point was also raised, namely that the ui should not leak
**how** it does things, but rather what the **end effect** is. The new
flag uses the proposed naming. This is of course something that can be
iterated on further before stabilization.
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.
