Print a message when panicking from mini_core

example/mini_core.rs

@@ -268,6 +268,7 @@ pub trait FnMut<Args>: FnOnce<Args> {
 #[lang = "panic"]
 pub fn panic(&(_msg, _file, _line, _col): &(&'static str, &'static str, u32, u32)) -> ! {
     unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
         intrinsics::abort();
     }
 }