bbPress.org

You can create a file called info.php and put this into it:

<?php

phpinfo();

?>

Then access that at http://www.example.com/bbpress/info.php and see if the getmypid function is disabled (just search that page for getmypid.) If it is, I imagine you can just remove that bit from class-phpass.php line 43.

$this->random_state = microtime() . getmypid();

In this instance, getmypid() just returns the pid of the process that called it and that is concatenated with microtime to provide a random number. You can use something else there and be fine, I think. Or, ask your host to enable it if it’s disabled.