fcntl module add FreeBSD's F_DUP2FD_CLOEXEC flag support.

Author: devnexen

Modules/fcntlmodule.c

@@ -581,6 +581,11 @@ all_ins(PyObject* m)
     if (PyModule_AddIntMacro(m, F_NOCACHE)) return -1;
 #endif
 
+/* FreeBSD specifics */
+#ifdef F_DUP2FD_CLOEXEC
+    if (PyModule_AddIntMacro(m, F_DUP2FD_CLOEXEC)) return -1;
+#endif
+
 /* For F_{GET|SET}FL */
 #ifdef FD_CLOEXEC
     if (PyModule_AddIntMacro(m, FD_CLOEXEC)) return -1;