…me attribute

This prevents the calculated name from going out of sync with
exported_symbols. It also avoids having to special case the panic_impl
lang item.

Rustup

To unblock rust-lang/miri#3688

Use the symbol_name query instead of trying to infer from the link_name attribute

This prevents the calculated name from going out of sync with exported_symbols. It also avoids having to special case the panic_impl lang item.

It also makes it easier to fix miri with rust-lang#127173.

Add syscall `dup()` for unix target

Add support for `dup()` and `dup2()`.

Fixes rust-lang#3454

Implement the `_mm256_zeroupper` and `_mm256_zeroall` intrinsics

These two intrinsics were missing from the original implementation of the AVX intrinsics.
Fortunately their implementation is trivial.

Automatic Rustup

…in circumstances

…end-write, r=RalfJung

TB: Refine protector end semantics

Tree Borrows has protector end tag semantics, namely that protectors ending cause a [special implicit read](https://perso.crans.org/vanille/treebor/diff.0.html) on all locations protected by that protector that have actually been accessed. See also rust-lang#3067.

While this is enough for ensuring protectors allow adding/reordering reads, it does not prove that one can reorder writes. For this, we need to make this stronger, by making this implicit read be a write in cases when there was a write to the location protected by that protector, i.e. if the permission is `Active`.

There is a test that shows why this behavior is necessary, see `tests/fail/tree_borrows/protector-write-lazy.rs`.