Module is not working if “apache_request_headers” is disabled

Hello,

module is not working (website is not working) if this conditions…
How to reproduce error:
1) webhosting has function “apache_request_headers” in “disabled_functions”.
2) php version 7.1 (and other 7.x will same I think)
Error:
Fatal error: Cannot redeclare apache_request_headers() in /var/www/wp-content/plugins/wp-super-cache/wp-cache-phase2.php on line 3226
There is fuction_exists – which returning true, because its disabled and module is trying to redeclare function.

Thank you for fix.