Changes related to update.php:
* Removed counter.php. Whoever heard of adding a file for a single line of code? Refactored the callers to GlobalFunctions.php wfCountDown().
* Removed the requirement for $wgDBadminuser to be set in update.php. There really is no security benefit, it's just there to annoy users and cause bugs like #19127. Just use $wgDBuser, commandLine.inc will automatically set it to $wgDBadminuser if it's available.
* Since we're using $wgDBuser now, we may as well just use wfGetDB(DB_MASTER) instead of the rubbish special-case code that was already there. There's no need for special-case error handling, there's already special-case code for command line connection errors, if you don't think that message is informative enough then you can change it there.
* Don't set $options before including commandLine.inc, it doesn't do anything.
* Use require not require_once