[Clang] Migrate llvm::make_unique to std::make_unique

Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.

Differential revision: https://reviews.llvm.org/D66259

llvm-svn: 368942
diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
index 3ba77f1..e85499c 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -629,7 +629,7 @@
   }
 
   std::unique_ptr<CorrectionCandidateCallback> clone() override {
-    return llvm::make_unique<RecordMemberExprValidatorCCC>(*this);
+    return std::make_unique<RecordMemberExprValidatorCCC>(*this);
   }
 
 private: