[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/ObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index def0b30..ff9b55d 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -330,7 +330,7 @@
 void ObjectLinkingLayer::emit(MaterializationResponsibility R,
                               std::unique_ptr<MemoryBuffer> O) {
   assert(O && "Object must not be null");
-  jitLink(llvm::make_unique<ObjectLinkingLayerJITLinkContext>(
+  jitLink(std::make_unique<ObjectLinkingLayerJITLinkContext>(
       *this, std::move(R), std::move(O)));
 }