bpo-40898: Remove redundant if statements in tp_traverse (GH-20692)

diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
index 18fcebd..3f2f716 100644
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -999,8 +999,7 @@
 static int
 cycle_traverse(cycleobject *lz, visitproc visit, void *arg)
 {
-    if (lz->it)
-        Py_VISIT(lz->it);
+    Py_VISIT(lz->it);
     Py_VISIT(lz->saved);
     return 0;
 }