Merging r213834:

Merging r213834:
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r213834 | rsmith | 2014-07-23 19:27:39 -0700 (Wed, 23 Jul 2014) | 4 lines

Take the canonical type when forming a canonical template argument with
'nullptr' value. Fixes profiling of such template arguments to always give the
same value.

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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_35@214751 91177308-0d34-0410-b5e6-96231b3b80d8