[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/LegacyDivergenceAnalysis.cpp b/llvm/lib/Analysis/LegacyDivergenceAnalysis.cpp
index 2fd8b8d..7a12f59 100644
--- a/llvm/lib/Analysis/LegacyDivergenceAnalysis.cpp
+++ b/llvm/lib/Analysis/LegacyDivergenceAnalysis.cpp
@@ -336,7 +336,7 @@
   if (shouldUseGPUDivergenceAnalysis(F)) {
     // run the new GPU divergence analysis
     auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
-    gpuDA = llvm::make_unique<GPUDivergenceAnalysis>(F, DT, PDT, LI, TTI);
+    gpuDA = std::make_unique<GPUDivergenceAnalysis>(F, DT, PDT, LI, TTI);
 
   } else {
     // run LLVM's existing DivergenceAnalysis