Add '!' to macro name suggestion, use fileline_help instead of span_help

src/libsyntax/ext/base.rs

@@ -790,7 +790,7 @@ impl<'a> ExtCtxt<'a> {
             }
         }
         if let Some((suggestion, _)) = min {
-            self.span_help(span, &format!("did you mean `{}`?", suggestion));
+            self.fileline_help(span, &format!("did you mean `{}!`?", suggestion));
         }
     }
 }

src/test/compile-fail/macro-name-typo.rs

@@ -10,5 +10,5 @@
 
 fn main() {
     printlx!("oh noes!"); //~ ERROR macro undefined
-    //~^ HELP did you mean `println`?
+    //~^ HELP did you mean `println!`?
 }