Auto merge of #32390 - japaric:untry, r=pnkfelix

convert 99.9% of `try!`s to `?`s

The first commit is an automated conversion using the [untry] tool and the following command:

```
$ find -name '*.rs' -type f | xargs untry
```

at the root of the Rust repo.

[untry]: https://github.com/japaric/untry

cc @rust-lang/lang @alexcrichton @brson