calls.
Revert the change to the sapi_add_header_ex interface.
Fix various bugs:
1. header("HTTP/1.0 306 foo");
header("Location: absolute-uri");
did not work in combination with several SAPI modules, because
http_status_line was never properly reset. And thus, all SAPI
modules which looked at http_status_line ignored the changed
http_response_code.
2. The CGI SAPI did not send out the HTTP status line at all, if
http_status_line had not been set explicitly by calling
header("HTTP/1.0 200 foo");
