[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/Analysis/OrderedInstructions.cpp b/llvm/lib/Analysis/OrderedInstructions.cpp
index 458c0a7..e947e5e 100644
--- a/llvm/lib/Analysis/OrderedInstructions.cpp
+++ b/llvm/lib/Analysis/OrderedInstructions.cpp
@@ -21,7 +21,7 @@
   const BasicBlock *IBB = InstA->getParent();
   auto OBB = OBBMap.find(IBB);
   if (OBB == OBBMap.end())
-    OBB = OBBMap.insert({IBB, make_unique<OrderedBasicBlock>(IBB)}).first;
+    OBB = OBBMap.insert({IBB, std::make_unique<OrderedBasicBlock>(IBB)}).first;
   return OBB->second->dominates(InstA, InstB);
 }