Revert "Use make_unique<T>(...) rather than unique_ptr<T>(new T(...))"

Seems to be crashing clang (3.3 and 3.4) on some buildbots...

This reverts commit r207792.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207799 91177308-0d34-0410-b5e6-96231b3b80d8