Fix a warning on OpenBSD.
Fix a warning on OpenBSD.

hehui199135/python-spidermonkey,davisp/python-spidermonkey,tempbottle/python-spidermonkey,tempbottle/python-spidermonkey,davisp/python-spidermonkey,hehui199135/python-spidermonkey,davisp/python-spidermonkey,tempbottle/python-spidermonkey,hehui199135/python-spidermonkey,tempbottle/python-spidermonkey,hehui199135/python-spidermonkey