Apply tex wrap/clamp in shader for render-to-tex

Fixes graphical artifacts in Wild Arms XF (which depends on how you get there, because it's based on the size of the framebuffer.)

I'm not really sure how to do projection... but I wonder if it's related to some of our shadow bugs.  Is it x/z, y/z?  That seems to help some artifacts but of course doesn't fix the offsetting.

-[Unknown]
Err, clamping to a smaller surface.

-[Unknown]