[llvm] 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.

llvm-svn: 369013
diff --git a/llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl06.rst b/llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl06.rst
index 911a7dc..a05ed0b 100644
--- a/llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl06.rst
+++ b/llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl06.rst
@@ -220,7 +220,7 @@
       if (Kind && ArgNames.size() != Kind)
         return LogErrorP("Invalid number of operands for operator");
 
-      return llvm::make_unique<PrototypeAST>(FnName, std::move(ArgNames), Kind != 0,
+      return std::make_unique<PrototypeAST>(FnName, std::move(ArgNames), Kind != 0,
                                              BinaryPrecedence);
     }
 
@@ -348,7 +348,7 @@
       int Opc = CurTok;
       getNextToken();
       if (auto Operand = ParseUnary())
-        return llvm::make_unique<UnaryExprAST>(Opc, std::move(Operand));
+        return std::make_unique<UnaryExprAST>(Opc, std::move(Operand));
       return nullptr;
     }