Also sort ERROR_BAD_NETPATH correctly.
Compared with the similar error code mapping in
libcxx/src/filesystem/operations.cpp, I'm leaving out
mappings for ERROR_NOT_SAME_DEVICE and ERROR_OPERATION_ABORTED.
They map nicely to std::errc::cross_device_link and
std::errc::operation_canceled, but those aren't available in
llvm::errc, as they aren't available across all platforms.
Also, the libcxx version maps ERROR_INVALID_NAME to
no_such_file_or_directory instead of invalid_argument.