[beta] Prepare beta 1.35.0

Also cherry-picked:

* #59835: Re-export NonZero signed variant in std

cc @Mark-Simulacrum  @rust-lang/release
r? @ghost

Old linkers are unable to decompress them and fail to link binaries

This is result of squashing two revert commits:

Revert "compile all crates under test w/ -Zemit-stack-sizes"

This reverts commit 7d365cf.

Revert "bootstrap: build compiler-builtins with -Z emit-stack-sizes"

This reverts commit 8b8488c.

It's a primitive slice method, not a standalone function.

[beta] Rollup backports

Cherry-picked:

* #59886:  musl: do not compress debug section
* #59891:  Fix the link to sort_by_cached_key
* #59911: Revert "compile crates under test w/ -Zemit-stack-sizes"
* #59978: rustdoc: Remove default keyword from re-exported trait methods
* #59989: Fix links to Atomic* in RELEASES.md
* #60186: Temporarily accept [i|u][32|size] suffixes on a tuple index and warn
* #60309: Add 1.34.1 release notes

Rolled up:

* #60273: [beta] bootstrap; remove redundant imports.

r? @ghost

See #58794 for context.

This reverts commit b4a6f59.

…lacrum

[beta] Permit unwinding through FFI by default

This repeats #59640 for Rust 1.35, as #58794 is not yet resolved.

cc @rust-lang/release
r? @Mark-Simulacrum

This commit destabilizes the `Error::type_id` function in the standard library.
This does so by effectively reverting #58048, restoring the `#[unstable]`
attribute. The security mailing list has recently been notified of a
vulnerability relating to the stabilization of this function. First stabilized
in Rust 1.34.0, a stable function here allows users to implement a custom
return value for this function:

    struct MyType;

    impl Error for MyType {
	fn type_id(&self) -> TypeId {
	    // Enable safe casting to `String` by accident.
	    TypeId::of::<String>()
	}
    }

This, when combined with the `Error::downcast` family of functions, allows
safely casting a type to any other type, clearly a memory safety issue! A
security announcement will be shortly posted to the security mailing list as
well as the Rust Blog, and when those links are available they'll be filled in
for this PR as well.

This commit simply destabilizes the `Error::type_id` which, although breaking
for users since Rust 1.34.0, is hoped to have little impact and has been deemed
sufficient to mitigate this issue for the stable channel. The long-term fate of
the `Error::type_id` API will be discussed at #60784.

…=pietroalbini

[beta] Destabilize the `Error::type_id` function

This commit destabilizes the `Error::type_id` function in the standard library.
This does so by effectively reverting #58048, restoring the `#[unstable]`
attribute. The security mailing list has recently been notified of a
vulnerability relating to the stabilization of this function. First stabilized
in Rust 1.34.0, a stable function here allows users to implement a custom
return value for this function:

    struct MyType;

    impl Error for MyType {
	fn type_id(&self) -> TypeId {
	    // Enable safe casting to `String` by accident.
	    TypeId::of::<String>()
	}
    }

This, when combined with the `Error::downcast` family of functions, allows
safely casting a type to any other type, clearly a memory safety issue! A
formal announcement has been made to the [security mailing list](https://groups.google.com/forum/#!topic/rustlang-security-announcements/aZabeCMUv70) as well as [the blog](https://blog.rust-lang.org/2019/05/13/Security-advisory.html)

This commit simply destabilizes the `Error::type_id` which, although breaking
for users since Rust 1.34.0, is hoped to have little impact and has been deemed
sufficient to mitigate this issue for the stable channel. The long-term fate of
the `Error::type_id` API will be discussed at #60784.

…r=pietroalbini

[beta] Rollup backports

Rolled up:

* #60806: [beta] save-analysis: Fix ICE when processing associated constant

Cherry-picked:

* #60837: Update release notes for 1.35.0
* #60657: Stabilize and re-export core::array in std

r? @ghost

[beta] Comment out dev key in stage0.txt

r? @pietroalbini

We should maybe have some check for this somewhere; I think this is at least the second time we've forgotten to do this. Maybe just have CI fail on beta branch unless it's commented (and not a release week?)?

Backports rust-lang/rust-clippy#4101