[llvm] r264425 - [Object] Start threading Error through MachOObjectFile construction.

[Rafael Espíndola via llvm-commits]

> Yeah - this will be pretty rare, and I want it to be ugly - nobody should
> use a pre-checked error except for the error-as-out-parameter idiom.
> Actually Error::errorAsOutParameter() sounds good. :)

And even that is only for constructors, right? Otherwise one should
use Expected.

In fact, using an std::error_code (or equivalent) as a parameter of
constructed always looked a bit odd IMHO. With good move constructors
we should be able to have trivial private constructors and always use
an static create method that returns an ErrorOr (or equivalent).

Cheers,
Rafael