[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/lib/ExecutionEngine/Orc/Layer.cpp b/llvm/lib/ExecutionEngine/Orc/Layer.cpp
index 2126ecb..ba2ec32 100644
--- a/llvm/lib/ExecutionEngine/Orc/Layer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Layer.cpp
@@ -19,7 +19,7 @@
 IRLayer::~IRLayer() {}
 
 Error IRLayer::add(JITDylib &JD, ThreadSafeModule TSM, VModuleKey K) {
-  return JD.define(llvm::make_unique<BasicIRLayerMaterializationUnit>(
+  return JD.define(std::make_unique<BasicIRLayerMaterializationUnit>(
       *this, std::move(K), std::move(TSM)));
 }