Remove redundant version_compare()

get_magic_quotes_gpc() exists in all versions of PHP and HHVM
and returns the correct value.

See http://php.net/manual/en/function.get-magic-quotes-gpc.php
and https://github.com/kohana/core/commit/f770108ba0e4b31c52997ff878353850e8ffaa42#commitcomment-2054200