Cannot redeclare drupal_get_hash_salt()
You've got definitely a Drupal upgrade problem, drupal_get_hash_salt used to be in common.inc and was moved to bootstrap.inc in Drupal 7.23 version as you can see in https://www.drupal.org/node/1739986.

Something went wrong with your core update, I'd suggest you to backup your data and upgrade your files to the latest version, then run update.php and check everything is OK.