Fix error message in crate_in_macro_def.stderr

Author: smoelius

tests/ui/crate_in_macro_def.stderr

@@ -1,14 +1,10 @@
-error: reference to the macro call's crate, which is rarely intended
+error: `crate` references the macro call's crate
   --> $DIR/crate_in_macro_def.rs:19:28
    |
 LL |             println!("{}", crate::unhygienic::MESSAGE);
-   |                            ^^^^^
+   |                            ^^^^^ help: to reference the macro definition's crate, use: `$crate`
    |
    = note: `-D clippy::crate-in-macro-def` implied by `-D warnings`
-help: if reference to the macro definition's crate is intended, use
-   |
-LL |             println!("{}", $crate::unhygienic::MESSAGE);
-   |                            ~~~~~~
 
 error: aborting due to previous error