[patch][rfc] Add pwrite to raw_stream

[Rafael Espíndola]

On 8 April 2015 at 20:25, Sean Silva <chisophugis at gmail.com> wrote:
> It stops being a "stream" when you add the ability to write at a specified
> offset. It's like adding operator+= to something with "outputiterator" in
> the name. Is there a reason that this has to live inside raw_ostream?

The object writer has to write to something. It can do it better if
that something supports at least pwrite.

We can rename it, but seems a bit heavy handed.

Cheers,
Rafael