[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/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index e202b45..d0f89dc 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -808,7 +808,7 @@
     auto *MSSAAnalysis = getAnalysisIfAvailable<MemorySSAWrapperPass>();
     if (MSSAAnalysis) {
       MSSA = &MSSAAnalysis->getMSSA();
-      MSSAU = make_unique<MemorySSAUpdater>(MSSA);
+      MSSAU = std::make_unique<MemorySSAUpdater>(MSSA);
     }
   }
 
@@ -839,7 +839,7 @@
   std::unique_ptr<MemorySSAUpdater> MSSAU;
   if (MSSAAnalysis) {
     auto *MSSA = &MSSAAnalysis->getMSSA();
-    MSSAU = make_unique<MemorySSAUpdater>(MSSA);
+    MSSAU = std::make_unique<MemorySSAUpdater>(MSSA);
   }