[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/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index afe48bf..6ba8c48 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -570,7 +570,7 @@
   }
 
   userValues.push_back(
-      llvm::make_unique<UserValue>(Var, Expr, DL, allocator));
+      std::make_unique<UserValue>(Var, Expr, DL, allocator));
   UserValue *UV = userValues.back().get();
   Leader = UserValue::merge(Leader, UV);
   return UV;
@@ -666,7 +666,7 @@
     }
   }
   if (!Found)
-    userLabels.push_back(llvm::make_unique<UserLabel>(Label, DL, Idx));
+    userLabels.push_back(std::make_unique<UserLabel>(Label, DL, Idx));
 
   return true;
 }