Fix the multiple attachment types in fbo.rs
Fix the multiple attachment types in fbo.rs

cpjreynolds/glium,bvssvni/glium,rozaliev/glium,acolley/glium,carbidegames/glium,caldwell/glium,msiglreith/glium,nicokoch/glium,tomaka/glium,christopheraugustus/glium,glium/glium,sdotz/glium,binsoftware/glium,TyOverby/glium