Use std::unique_ptr to make the ownership explicit.

llvm-svn: 214377
diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index f44b0e3..414205a 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -74,12 +74,13 @@
     return;
   }
 
-  ErrorOr<ObjectFile *> ObjOrErr(ObjectFile::createObjectFile(Buff.get()));
+  ErrorOr<std::unique_ptr<ObjectFile>> ObjOrErr =
+      ObjectFile::createObjectFile(Buff.get());
   if (std::error_code EC = ObjOrErr.getError()) {
     errs() << Filename << ": " << EC.message() << '\n';
     return;
   }
-  std::unique_ptr<ObjectFile> Obj(ObjOrErr.get());
+  std::unique_ptr<ObjectFile> Obj = std::move(ObjOrErr.get());
 
   std::unique_ptr<DIContext> DICtx(DIContext::getDWARFContext(Obj.get()));