Use error_code() instead of error_code::succes()

There is no std::error_code::success, so this removes much of the noise
in transitioning to std::error_code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209952 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Object/Archive.cpp

@@ -179,7 +179,7 @@ error_code Archive::Child::getMemoryBuffer(std::unique_ptr<MemoryBuffer> &Result
                                   .toStringRef(Path)
                             : Name,
       false));
-  return error_code::success();
+  return error_code();
 }
 
 error_code Archive::Child::getAsBinary(std::unique_ptr<Binary> &Result,