Fixes rust-lang#89177

The suggestion checked if Pin<Box<T>> could be coeerced to the expected
type, but did not check predicates created by the coercion. We now
look for predicates that definitely cannot be satisfied before giving
the suggestion.

The suggestion is marked MaybeIncorrect because we allow predicates that
are still ambiguous and can't be proven.

This only changed two tests and I consider both changes an improvement.

Fix incorrect Box::pin suggestion

The suggestion checked if `Pin<Box<T>>` could be coeerced to the expected
type, but did not check predicates created by the coercion. We now
look for predicates that definitely cannot be satisfied before giving
the suggestion.

The suggestion is still marked MaybeIncorrect because we allow predicates that
are still ambiguous and can't be proven.

Fixes rust-lang#72117.

Fix ctrl-c causing reads of stdin to return empty on Windows.

Pressing ctrl+c (or ctrl+break) on Windows caused a blocking read of stdin to unblock and return empty, unlike other platforms which continue to block.

On ctrl-c, `ReadConsoleW` will return success, but also set `LastError` to `ERROR_OPERATION_ABORTED`.

This change detects this case, and re-tries the call to `ReadConsoleW`.

Fixes rust-lang#89177. See issue for further details.

Tested on Windows 7 and Windows 10 with both MSVC and GNU toolchains

Switch order of terms to prevent overflow

Fixes rust-lang#89639

r? ``@pnkfelix``

Allow static linking LLVM with ThinLTO

There's no reason not to allow this if the user wants it. It works, at least in a local build on linux host.

For our use case, we're happy to spend more time building the compiler if it creates a speedup every time we run it, and we've observed speedups like this with clang.

Add missing word to `FromStr` trait documentation

The doc comment is getting a bit wide, let me know if I should restructure it/add a new line.

…, r=notriddle

Fix missing remaining compiler specific cfg information

Follow-up of rust-lang#89596. We forgot a few of them:

![Screenshot from 2021-10-14 11-36-44](https://user-images.githubusercontent.com/3050060/137292700-64ebc59f-d9d2-41f2-be3a-fa5bf211523c.png)
![Screenshot from 2021-10-14 11-36-56](https://user-images.githubusercontent.com/3050060/137292703-f63fa4e5-2c56-446b-9f86-3652f03dfe59.png)

r? `@notriddle`