check-pass test for a MRE of rust-lang#135020

Signed-off-by: FedericoBruzzone <[email protected]>

Author: FedericoBruzzone

tests/crashes/135020.rs

@@ -0,0 +1,7 @@
+//@ check-pass
+
+fn problem_thingy(items: &mut impl Iterator<Item = str>) {
+    items.peekable();
+}
+
+fn main() {}