PHP 5.4.x uses a different library to support mysqli, new=mysqlnd, old= libmysql. I don't fully understand the impact on lampp at this point.
http://php.net/manual/en/mysqli.installation.php
According to the phpinfo() it appears to have been correctly compiled for the new library
'--with-mysql=mysqlnd'
'--with-mysqli=mysqlnd'
I don't think you need to add the extension/so to the php.ini as they are 'compile withs' - AFAIK that means the code is hard-linked in.
I am seeking wisdom (or correction).
Thanks and good luck
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