[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/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index 886ae7e..cd70792 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -139,7 +139,7 @@
 
     std::unique_ptr<MCAsmBackend> MAB(
         getTarget().createMCAsmBackend(STI, MRI, Options.MCOptions));
-    auto FOut = llvm::make_unique<formatted_raw_ostream>(Out);
+    auto FOut = std::make_unique<formatted_raw_ostream>(Out);
     MCStreamer *S = getTarget().createAsmStreamer(
         Context, std::move(FOut), Options.MCOptions.AsmVerbose,
         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, std::move(MCE),