bpo-31893: Fix errors in b9052a0f. (GH-4196) (#4201)

* Fix a compilation error on FreeBSD.
* Fix the data attribute size on Mac OS X.
(cherry picked from commit 2298fad5)

Modules/selectmodule.c

@@ -1841,12 +1841,12 @@ static PyTypeObject kqueue_queue_Type;
 #   define FFLAGS_FMT_UNIT  "I"
 #endif
 
-#ifdef __FreeBSD__
-#   define DATA_TYPE        T_INTPTRT
-#   define DATA_FMT_UNIT    INTPTR_FMT_UNIT
-#else
+#if defined(__NetBSD__) || defined(__OpenBSD__)
 #   define DATA_TYPE        T_INT64
 #   define DATA_FMT_UNIT    INT64_FMT_UNIT
+#else
+#   define DATA_TYPE        T_INTPTRT
+#   define DATA_FMT_UNIT    INTPTRT_FMT_UNIT
 #endif
 
 /* Unfortunately, we can't store python objects in udata, because