Add regression test for #95230

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

src/test/ui/hrtb/issue-95230.rs

@@ -0,0 +1,7 @@
+// check-pass
+
+pub struct Bar
+where
+    for<'a> &'a mut Self:;
+
+fn main() {}