[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/IPO/ThinLTOBitcodeWriter.cpp b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
index 31c731e7..690b5e8 100644
--- a/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ b/llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -466,7 +466,7 @@
       // splitAndWriteThinLTOBitcode). Just always build it once via the
       // buildModuleSummaryIndex when Module(s) are ready.
       ProfileSummaryInfo PSI(M);
-      NewIndex = llvm::make_unique<ModuleSummaryIndex>(
+      NewIndex = std::make_unique<ModuleSummaryIndex>(
           buildModuleSummaryIndex(M, nullptr, &PSI));
       Index = NewIndex.get();
     }