Rollup merge of #103536 - Enselic:remove-set_sigpipe_handler, r=tmiasko

Rollup merge of #103536 - Enselic:remove-set_sigpipe_handler, r=tmiasko

Remove `rustc_driver::set_sigpipe_handler()`

Its usage was removed in https://github.com/rust-lang/rust/pull/102587 and https://github.com/rust-lang/rust/pull/103495, so we do not need to keep it around any longer. According to [preliminary input](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Find.20.60rustc_driver.60.20dependent.20projects.3F/near/304490764), we do not need to worry about any deprecation cycle for this explicitly unstable API, and can just straight up remove it.

PR that added `set_sigpipe_handler`: https://github.com/rust-lang/rust/pull/49606

Tracking issue for `unix_sigpipe`: #97889

Migration instructions for any remaining clients
---

Change from

```rust
#![feature(rustc_private)]

extern crate rustc_driver;

fn main() {
    rustc_driver::set_sigpipe_handler();
    // ...
```

to

```rust
#![feature(unix_sigpipe)]

#[unix_sigpipe = "sig_dfl"]
fn main() {
    // ...
```

``@rustbot`` labels +T-compiler