Arch Linux use https://downloads.sourceforge.net/sourceforge/curlftpfs/curlftpfs-0.9.2.tar.gz as the source, and the tarball contains the config.{sub, guess} Thanks for your reply! I will try to update the source for Arch Linux.
GNU config is too old to build on RISC-V
GNU config is too old to build on RISC-V