Fix help for duplicated names: extern crate (...) as (...)

On the case of duplicated names caused by an `extern crate` statement
with a rename, don't include the inline suggestion, instead using a span
label with only the text to avoid incorrect rust code output.

src/test/compile-fail/E0259.rs

@@ -18,5 +18,6 @@ extern crate libc as alloc;
 //~^ ERROR E0259
 //~| NOTE `alloc` reimported here
 //~| NOTE `alloc` must be defined only once in the type namespace of this module
+//~| NOTE You can use `as` to change the binding name of the import
 
 fn main() {}