Add equivalent test in src/test/rustdoc

Author: Urgau

src/test/rustdoc/issue-89852.rs

@@ -0,0 +1,14 @@
+// edition:2018
+
+#![no_core]
+#![feature(no_core)]
+
+// @count issue_89852/index.html '//*[@class="macro"]' 2
+// @has - '//*[@class="macro"]/@href' 'macro.repro.html'
+#[macro_export]
+macro_rules! repro {
+    () => {};
+}
+
+// @!has issue_89852/macro.repro.html '//*[@class="macro"]/@content' 'repro2'
+pub use crate::repro as repro2;