Failing test to show that requires_renaming recurses

requires_renaming must not recurse into array subtypes in structs.

Author: tautschnig

regression/cbmc/struct13/main.c

@@ -0,0 +1,12 @@
+struct S
+{
+  struct S *s;
+  struct S *a[2];
+};
+
+int main()
+{
+  struct S s;
+  s.s = 0;
+  return 0;
+}

regression/cbmc/struct13/test.desc

@@ -0,0 +1,12 @@
+KNOWNBUG
+main.c
+
+^EXIT=0$
+^SIGNAL=0$
+^VERIFICATION SUCCESSFUL$
+--
+^warning: ignoring
+--
+Just like pointers, array members may have subtypes of the same type as the
+containing struct. requires_renaming fails to catch this case, which results in
+unbounded recursion.