LLVM TargetMachines default to using the (now-legacy) .ctors
representation of init functions. Mixing .ctors and .init_array
representations can cause issues when linking with lld.

This happens in practice for:

* Our profiling runtime which is currently implicitly built with
  .init_array since it is built by clang, which sets this field.
* External C/C++ code that may be linked into the same process.

To support legacy systems which may use .ctors, targets may now specify
that they use .ctors via the use_ctors attribute which defaults to
false.

For debugging and manual control, -Z use-ctors-section=yes/no will allow
manual override.

Fixes: rust-lang#71233

upgrade chalk and use chalk-solve/chalk-ir/chalk-rust-ir

Reintegrate chalk into rustc.

r? @nikomatsakis
cc. @rust-lang/wg-traits

Move tests from `test/run-fail` to UI

Fixes rust-lang#65440
cc rust-lang#65865 rust-lang#65506
r? @nikomatsakis

rustllvm: Use .init_array rather than .ctors

LLVM TargetMachines default to using the (now-legacy) .ctors
representation of init functions. Mixing .ctors and .init_array
representations can cause issues when linking with lld.

This happens in practice for:

* Our profiling runtime which is currently implicitly built with
  .init_array since it is built by clang, which sets this field.
* External C/C++ code that may be linked into the same process.

Fixes: rust-lang#71233

Simplify the `tcx.alloc_map` API

This PR changes all functions that require manually locking the `alloc_map` to functions on `TyCtxt` that lock the map internally. In the same step we make the `TyCtxt::alloc_map` field private.

r? @RalfJung

Remove ast::{Ident, Name} reexports.

The reexport of `Symbol` into `Name` confused me.