Fix test case

Cf. <#4687>.

Author: cmb69

ext/date/tests/DatePeriod_set_state.phpt

@@ -58,7 +58,7 @@ object(DatePeriod)#%d (6) {
     ["invert"]=>
     int(0)
     ["days"]=>
-    int(0)
+    bool(false)
     ["special_type"]=>
     int(0)
     ["special_amount"]=>