rustc: Add crust functions to the AST

src/comp/syntax/ast.rs

@@ -407,6 +407,7 @@ enum purity {
     pure_fn, // declared with "pure fn"
     unsafe_fn, // declared with "unsafe fn"
     impure_fn, // declared with "fn"
+    crust_fn, // declared with "crust fn"
 }
 
 enum ret_style {

src/comp/syntax/print/pprust.rs

@@ -1199,6 +1199,7 @@ fn print_fn(s: ps, decl: ast::fn_decl, name: ast::ident,
       ast::impure_fn { head(s, "fn"); }
       ast::unsafe_fn { head(s, "unsafe fn"); }
       ast::pure_fn { head(s, "pure fn"); }
+      ast::crust_fn { head(s, "crust fn"); }
     }
     word(s.s, name);
     print_type_params(s, typarams);