util: Unset LC_* variables as they may be unset at login time
Otherwise, a switch from a mixed locale where LANG != REGION(/FORMAT) to a non-mixed environment where LANG == REGION(/FORMAT) may result in LC_* surviving in systemd and the change not getting applied.
Similar issues might occur when other DEs are setting these variables before a login into GNOME happens.
Closes: #85 (closed)