ArteS [1] filed a deletion request for engine_pkcs11 [2]: The engine_pkcs11 library has been merged into https://github.com/OpenSC/libp11 version 0.4.0 and later. For the time being, this repository is left intact to retain the history of changes before made prior to the merge.
[1] https://aur.archlinux.org/account/ArteS/ [2] https://aur.archlinux.org/pkgbase/engine_pkcs11/
