Revive L4Re target

[farao]

This revives the target for the L4Re OS. It changes the way, linking is done and adds aarch64 support and documentation including a maintainer for the target.

The update of the libc crate is necessary since only in 0.2.179 and higher is the fixed support for L4Re on uclibc.

[rustbot]

Some changes occurred in src/doc/rustc/src/platform-support

cc @Noratrieb

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.

These commits modify compiler targets.
(See the Target Tier Policy.)

[rustbot]

r? @joboet

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[rustbot]

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

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

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

Some changes occurred in GUI tests.

cc @GuillaumeGomez

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @lolbinarycat

[GuillaumeGomez]

Wrong rebase.

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[farao]

Sorry for rebasing on an old commit by mistake

[rust-bors]

☔ The latest upstream changes (presumably #151107) made this pull request unmergeable. Please resolve the merge conflicts.