from: $server = $recaptcha_api_ssl_server;
to: $server = $recaptcha_api_secure_server;
instead of changing line 39 as proposed.
It might be useful then to change line 109 as well.
from: global $recaptcha_api_server, $recaptcha_api_ssl_server;
to: global $recaptcha_api_server, $recaptcha_api_secure_server;
J.