mint-helix: Disable RTCW's target_speaker spawnflag 16

RTCW's handling of target_speaker spawnflags & 16 pervents loading 4 SoF2 SP maps.
So I've disabled it.

spawnflags & 16 isn't implemented by SoF2 MP, JK2, or JA. I don't know what,
if anything, SoF2 SP expects it to do.