Remove some pointless environment variable checks for setting a callsign.
Remove some pointless environment variable checks for setting a callsign.

khonkhortisan/bzflag,kongr45gpen/bzflag,kongr45gpen/bzflag,khonkhortisan/bzflag,adamsdadakaeti/bzflag,kongr45gpen/bzflag,khonkhortisan/bzflag,kongr45gpen/bzflag,adamsdadakaeti/bzflag,adamsdadakaeti/bzflag,khonkhortisan/bzflag,kongr45gpen/bzflag,kongr45gpen/bzflag,adamsdadakaeti/bzflag,adamsdadakaeti/bzflag,khonkhortisan/bzflag,kongr45gpen/bzflag,kongr45gpen/bzflag,adamsdadakaeti/bzflag,khonkhortisan/bzflag,khonkhortisan/bzflag,adamsdadakaeti/bzflag