Merge pull request #21262 from steveklabnik/update_test

Update syntax of ignored test.

Reviewed-by: alexcrichton

Author: bors

src/test/compile-fail/unsupported-cast.rs

@@ -14,5 +14,5 @@
 extern crate libc;
 
 fn main() {
-  println!("{}", 1.0 as *libc::FILE); // Can't cast float to foreign.
+  println!("{:?}", 1.0 as *const libc::FILE); // Can't cast float to foreign.
 }