eprint -> eprintln to add trailing newline

src/librustc_errors/annotate_rs_emitter.rs

@@ -206,7 +206,7 @@ impl AnnotateRsEmitterWriter {
             // FIXME(#59346): Figure out if we can _always_ print to stderr or not.
             // `emitter.rs` has the `Destination` enum that lists various possible output
             // destinations.
-            eprint!("{}", dlf.format(&dl));
+            eprintln!("{}", dlf.format(&dl));
         };
     }
 }

src/test/ui/annotate-snippet/missing-type.stderr

@@ -3,4 +3,4 @@ error[E0412]: cannot find type `Iter` in this scope
   |
 4 |     let x: Iter;
   |            ^^^^ not found in this scope
-  |
+  |