Update the backtrace crate in libstd

[alexcrichton]

This commit updates the backtrace crate in libstd now that dependencies
have been updated to use memchr from the standard library as well.
This is mostly just making sure deps are up-to-date and have all the
latest-and-greatest fixes and such.

Closes rust-lang/backtrace-rs#432

[rust-highfive]

r? @Mark-Simulacrum

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[rust-highfive]

⚠️ Warning ⚠️

• These commits modify submodules.

[hkratz]

It seems that the update makes it impossible to build std with the backtrace feature disabled, e.g. with backtrace=false in config.toml or with cargo +nightly build -Z build-std -Zbuild-std-features=panic-unwind,default:

error[E0433]: failed to resolve: use of undeclared crate or module `object`
 --> library/std/src/../../backtrace/src/symbolize/gimli/macho.rs:4:5
  |
4 | use object::read::macho::{MachHeader, Nlist, Section, Segment as _};
  |     ^^^^^^ use of undeclared crate or module `object`

I rather liked this because it shaved of a bit of executable size while keeping unwinding on panics.

[alexcrichton]

Oh that's an unintended consequence of a historical refactoring in the crate, rust-lang/backtrace-rs#433 should restore support.

[alexcrichton]

Ok, I've updated the submodule here to include that fix.

[Mark-Simulacrum]

@bors r+ rollup=never

[bors]

📌 Commit 4a3e736 has been approved by Mark-Simulacrum

[bors]

⌛ Testing commit 4a3e736 with merge 7960030...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 7960030 to master...

[Mark-Simulacrum]

This was a perf regression, on a number of crates, but I believe it to be entirely or largely due to more metadata decoding and related processing of std, which this PR increased the size of.

@rustbot label perf-regression perf-regression-triaged