add private module override re-export test

Author: el-ev

tests/rustdoc/private-mod-override-re-export.rs

@@ -0,0 +1,14 @@
+// https://github.com/rust-lang/rust/issues/60926
+#![crate_name = "foo"]
+#![crate_type = "lib"]
+
+mod m1 {
+    pub mod m2 {
+        pub struct Foo;
+    }
+}
+
+pub use m1::*;
+use crate::m1::m2;
+
+//@ !has foo/index.html '//a[@href="m2/index.html"]' 'm2'