core: Remove transitional code

Author: catamorphism

src/libcore/extfmt.rs

@@ -499,12 +499,6 @@ pub mod rt {
 
     pub enum Ty { TyDefault, TyBits, TyHexUpper, TyHexLower, TyOctal, }
 
-    #[cfg(stage0)]
-    pub type Conv = {flags: u32, width: Count, precision: Count, ty: Ty};
-
-    #[cfg(stage1)]
-    #[cfg(stage2)]
-    #[cfg(stage3)]
     pub struct Conv {
         flags: u32,
         width: Count,