Add print in BacktraceFmt

[chenyukang]

I'm not sure whether we have better solution for those string don't belong to frames.

This is for rust-lang/rust#111730
I will make a follow-up PR for rustc if this is approved.

[chenyukang]

@JohnTitor
Seems the CI in this repo is broken.

[chenyukang]

@Amanieu
could you please help me reviewing this PR?

[Amanieu]

Can you fix the rustfmt failure?

[chenyukang]

Can you fix the rustfmt failure?

Fixed fmt, some CIs are still failing.

[Amanieu]

Can you rebase? The CI should be mostly fixed now. You can ignore the failures on Android, those are tracked by #531.

[chenyukang]

rebased, seems all the error are the same:

error: private item shadows public glob re-export
  --> crates/as-if-std/src/lib.rs:8:1
   |
8  | extern crate alloc;
   | ^^^^^^^^^^^^^^^^^^^
   |
note: the name `alloc` in the type namespace is supposed to be publicly re-exported here
  --> crates/as-if-std/src/lib.rs:[17](https://github.com/rust-lang/backtrace-rs/actions/runs/5314493838/jobs/9621774920?pr=527#step:7:18):9
   |
17 | pub use __internal::*;
   |         ^^^^^^^^^^^^^
note: but the private item here shadows it
  --> crates/as-if-std/src/lib.rs:8:1
   |
8  | extern crate alloc;
   | ^^^^^^^^^^^^^^^^^^^
   = note: `-D hidden-glob-reexports` implied by `-D warnings`

[Amanieu]

You didn't rebase.

[chenyukang]

You didn't rebase.

oh, sorry, I forget to add upstream as remote 🤔
Done.

[chenyukang]

This macos-latest, nightly seems not stable:

Run rustup update nightly --no-self-update && rustup default nightly
info: syncing channel updates for 'nightly-x86_6[4](https://github.com/rust-lang/backtrace-rs/actions/runs/5321733568/jobs/9637224693#step:3:5)-apple-darwin'
info: update not yet available, sorry! try again later
error: toolchain 'nightly-x8[6](https://github.com/rust-lang/backtrace-rs/actions/runs/5321733568/jobs/9637224693#step:3:7)_64-apple-darwin' is not installable
Error: Process completed with exit code 1.