[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/unittests/AST/RecursiveASTVisitorTest.cpp b/clang/unittests/AST/RecursiveASTVisitorTest.cpp
index 861b994..988a8ce 100644
--- a/clang/unittests/AST/RecursiveASTVisitorTest.cpp
+++ b/clang/unittests/AST/RecursiveASTVisitorTest.cpp
@@ -42,7 +42,7 @@
       llvm::function_ref<void(ASTContext &CTx)> Process;
     };
 
-    return llvm::make_unique<Consumer>(Process);
+    return std::make_unique<Consumer>(Process);
   }
 
 private: