[llvm-mca] Partially revert r346417.

Restored the llvm:: namespace qualifier on make_unique.
This removes the ambiguity with make_unique.  


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346424 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed