backtrace: report real path to core / std source code about probe-run

[japaric]

/rustc/9bc8c42bb2f19e745a63f3445f1ac248fb015e53/src/libcore/panicking.rs:92

it's not straightforward to map the git hash in this path to a local rust-src component (Rust source code)

It may be most accurate to change these paths into https://github.com/rust-lang/rust/blob/9bc8c42bb2f19e745a63f3445f1ac248fb015e53/library/core/src/panicking.rs#L92 but this can't be opened in VS code.

The rust-docs component provides a file in $(rustc --print sysroot)/share/doc/rust/html/version_info.html with these contents:

<div id="versioninfo">
  <img src="https://www.rust-lang.org/logos/rust-logo-32x32-blk.png" width="32" height="32" alt="Rust logo"><br>
  <span class="white-sticker"><a href="https://www.rust-lang.org">Rust</a> 1.52.1</span><br>
  <a href="https://github.com/rust-lang/rust/commit/9bc8c42bb2f19e745a63f3445f1ac248fb015e53"
    class="hash white-sticker">9bc8c42bb</a>
</div>

The info therein can be used to check if any of the installed Rust toolchains has the same git hash as the one in the rust-std paths stored in the debuginfo.

[japaric]

On the other hand it seems that rustc debug info remapping sometimes works and automatically maps /rustc/ paths into local paths that point into the rust-src component as seen in #201 but I can't repro