Swap render targets when drawing spline/beziers

Jeanne d'Arc draws to some framebuffers entirely using beziers, so without this it'll never switch.  I was kinda puzzled looking at the GE debugger, then the display list, then the GE debugger... until I realized it just wasn't even checking, heh.

Alone, this does not fix #1283, it's only half of the problem.  But, it's definitely correct anyway.  It could affect other games that use beziers heavily.

I also made it frameskip bezier/spline as it does other prims... I assume this is the right way.

-[Unknown]