Followup to mantis 3009; missed the Lead Sight gauge in the 1st fix

Rechecked all other gauges that set slew=true in their contructors
(vs 1st pass which checked gauges that set slew=true in hudparse.cpp)
I think I got them all now...

git-svn-id: svn://svn.icculus.org/fs2open@10476 387891d4-d844-0410-90c0-e4c51a9137d3