Update memchr to 2.7.6

[neuschaefer]

memchr 2.7.6 contains a bugfix for aarch64_be.

Note: I'm not sure about how dependency updates are managed in rust.git. If something should go through another branch or will happen automatically, please let me know.

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

The Miri subtree was changed

cc @rust-lang/miri

These commits modify the library/Cargo.lock file. Unintentional changes to library/Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

stdarch is developed in its own repository. If possible, consider making this change to rust-lang/stdarch instead.

cc @Amanieu, @folkertdev, @sayantn

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

[rustbot]

r? @marcoieni

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[lnicola]

If it's not urgent, please file the r-a change upstream, to avoid Cargo.lock conflicts.

[folkertdev]

For stdarch updating either here or in the repo is fine, though yeah for Cargo.lock conflicts updating in the repo itself is probably cleaner given that stdarch should only use memchr for tests.

The issue that is fixed in BurntSushi/memchr#188 reminds me of rust-lang/stdarch#1904 where we're also seeing some confusing behavior on aarch64_be, but we're not quite sure yet what the problem is given that currently our tests do pass with what we believe is an incorrect implementation.

[neuschaefer]

Alright, I'll go through the respective trees for rust-analyzer and stdarch.

rust-lang/stdarch#1904 is interesting, I only became aware of it today. I'll keep watching it to see which decision is made, and how it might make the change in memchr 2.7.6 invalid after all.