Add trailing newline to satisfy tidy

Author: oli-obk

src/test/ui/consts/min_const_fn/cast_errors.rs

@@ -11,4 +11,4 @@ const fn closure2() {
 const fn reify(f: fn()) -> unsafe fn() { f }
 //~^ ERROR function pointers in const fn are unstable
 const fn reify2() { main as unsafe fn(); }
-//~^ ERROR function pointers in const fn are unstable
+//~^ ERROR function pointers in const fn are unstable