Merging r277743:

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r277743 | bader | 2016-08-04 11:06:27 -0700 (Thu, 04 Aug 2016) | 12 lines

[OpenCL] Added underscores to the names of 'to_addr' OpenCL built-ins.

Summary:
In order to re-define OpenCL built-in functions
'to_{private,local,global}' in OpenCL run-time library LLVM names must
be different from the clang built-in function names.

Reviewers: yaxunl, Anastasia

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D23120
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llvm-svn: 278019