Various small fixes

[KJeff01]

While doing the convert var to let/const work I discovered a few things:

1. camSetVtolSpawnState() wouldn't work entirely right when object labels were passed and it would exit early.
2. NEXUS originally didn't use too many sound effects on Gamma 5, so I added yet another unused one for production.
3. The outro would force a skip if sequences weren't installed (obviously don't attempt to play if none are installed).
4. Fallout from the ModeQueue patch rendered libcampaign truck building broken for those that required positions.