rustdoc::broken_intra_doc_links: no backticks = use old behavior

this is in an effort to reduce the amount of code churn caused by
this lint triggering on text that was never meant to be a link.

a more principled hierustic for ignoring lints is not possible
without extensive changes, due to the lint emitting code
being so far away from the link collecting code,
and the fact that only the link collecting code
has access to details about how the link appears in the
unnormalized markdown.

Author: lolbinarycat

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -996,7 +996,9 @@ fn preprocess_link(
         }
     };
 
-    if can_be_url && should_ignore_link(path_str) {
+    // If there's no backticks, be lenient revert to old behavior.
+    // This is to prevent churn by linting on stuff that isn't meant to be a link.
+    if (can_be_url || !ori_link.link.contains('`')) && should_ignore_link(path_str) {
         return None;
     }