Rollup merge of rust-lang#43632 - ruuda:allow-long-relative-urls, r=Mark-Simulacrum

Detect relative urls in tidy check

This came up in rust-lang#43631: there can be long relative urls in Markdown comments, that do not start with `http://` or `https://`, so the tidy check will not detect them as urls and complain about the line length. This PR adds detection of relative urls starting with `../`.

Author: MaloJaffre

src/tools/tidy/src/style.rs

@@ -83,7 +83,7 @@ fn line_is_url(line: &str) -> bool {
                 => state = EXP_END,
 
             (EXP_URL, w)
-                if w.starts_with("http://") || w.starts_with("https://")
+                if w.starts_with("http://") || w.starts_with("https://") || w.starts_with("../")
                 => state = EXP_END,
 
             (_, _) => return false,