Update std::error example

[Hoverbear]

To not use old_io and os, which are deprecated. Since there is no more MemoryMap used byte parsing instead to generate the second potential error.

You can see the code working fine here on the PlayPen.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @aturon (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see CONTRIBUTING.md for more information.

[Hoverbear]

Whoops... Trailing whitespace. My bad. I'll fix this in a few minutes.

[Hoverbear]

The build got an error on submodule update and needs to be restarted.

[frewsxcv]

I'm personally not a fan of things being compressed to one line

[Hoverbear]

Formatting was done by the format button on playpen.

[steveklabnik]

This should be over four lines

[steveklabnik]

r=me after the nit, thank you!

(the playpen formatter is not perfect)

[Hoverbear]

r= @steveklabnik

[Manishearth]

@bors: r=steveklabnik rollup

[bors]

📌 Commit d4b5f65 has been approved by steveklabnik