Merge OpenCL 2.0 Pipe builtins (r258782) in 3.8

[Hans Wennborg via cfe-commits]

Sorry for the slow reply.

I've replied on the r258782 thread.

On Tue, Jan 26, 2016 at 10:29 AM, Anastasia Stulova
<Anastasia.Stulova at arm.com> wrote:
> Could you please merge Clang commit r258782 into release 3.8.
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> It adds Pipe BIFs to be used along with Pipe type committed earlier (in
> r257254).
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> Thanks,
>
> Anastasia