This essentially reverts part of rust-lang#6204.

This allows us to use the C++ compiler configured via
`CXX_target_triple` env vars

This allows moving a lot of run-make-fulldeps tests to just run-make
tests, and allows running those on target-only platforms

Somewhat hacky to reuse `tools.mk` like this, we should probably migrate
most of them now

…tsakis

Permit uninhabited enums to cast into ints

This essentially reverts part of rust-lang#6204; it is unclear why that [commit](rust-lang@c0f587d) was introduced, and I suspect no one remembers.

The changed code was only called from casting checks and appears to not affect any callers of that code (other than permitting this one case).

Fixes rust-lang#75647.

…bi-arm64-target-triple, r=nikomatsakis

Add support for Arm64 Catalyst on ARM Macs

This is an iteration on rust-lang#63467 which was merged a while ago. In the aforementioned PR, I added support for the `X86_64-apple-ios-macabi` target triple, which is Catalyst, iOS apps running on macOS.

Very soon, Apple will launch ARM64 based Macs which will introduce `aarch64_apple_darwin.rs`, macOS apps using the Darwin ABI running on ARM. This PR adds support for Catalyst apps on ARM Macs: iOS apps compiled for the darwin ABI.

I don't have access to a Apple Developer Transition Kit (DTK), so I can't really test if the generated binaries work correctly. I'm vaguely hopeful that somebody with access to a DTK could give this a spin.

… r=scottmcm,dtolnay

liballoc: VecDeque: Add binary search functions

I am submitting rust-lang/rfcs#2997 as a PR as suggested by @scottmcm

I haven't yet created a tracking issue - if there's a favorable feedback I'll create one and update the issue links in the unstable attribs.

…ports, r=ollie27

Remove compiler-synthesized reexports when documenting

Fixes rust-lang#77567

r? @ollie27

…, r=Mark-Simulacrum

Unignore test for rust-lang#36710 on MUSL

This now works fine thanks to autodetected `-C link-self-contained`.

Closes rust-lang#36710

…imulacrum

BTreeMap: improve gdb introspection of BTreeMap with ZST keys or values

I accidentally pushed an earlier revision in rust-lang#77788: it changes the index of tuples for BTreeSet from ""[{}]".format(i) to "key{}".format(i). Which doesn't seem to make the slightest difference on my linux box nor on CI. In fact, gdb doesn't make any distinction between "key{}" and "val{}" for a BTreeMap either, leading to confusing output if you test more. But easy to improve.

r? @Mark-Simulacrum

Set .llvmbc and .llvmcmd sections as allocatable

This marks both sections as allocatable rather than excluded, which matches what
clang does with the equivalent `-fembed-bitcode` flag.

…nikic

llvm: backport SystemZ fix for AGR clobbers

Fixes rust-lang#77382.

…crum

Bump bootstrap compiler

Mainly to bring in rust-lang#77953 to fix rust-lang/cargo#8517.