PHP: Don't load any ini files

By not loading any ini files (`-n`), startup errors are prevented from occurring.

like this:

    -> php -l -d error_reporting=E_ALL -d display_errors=0 -d error_log='' 'file.php'
    PHP Warning:  Module 'redis' already loaded in Unknown on line 0
    No syntax errors detected in file.php

The startup warning in the above example fools syntastic into thinking there are lint errors to process - this causes phpcs (and mess detector) checks to be skipped, yet as there's no actual lint error to display, nothing is displayed.

reference: @7fedd203e716c170efcf0c43a7e35406edef4aad (even though the code looks quite different now, and I can't trace where that logic is :))