change datatypes to unsigned
change datatypes to unsigned

avoiding warnings about sign conversion

Yubico/yubico-pam,eworm-de/yubico-pam,madrat-/yubico-pam,Yubico/yubico-pam,eworm-de/yubico-pam,madrat-/yubico-pam,Yubico/yubico-pam,madrat-/yubico-pam,eworm-de/yubico-pam