this is a ternary expression:
(get_magic_quotes_gpc()) ? $_GET['info_requests_id_rqt'] : addslashes($_GET['info_requests_id_rqt']);
it is basicly a short form of an if statement in the form of:
(question)?true part:false part;
in this case the question is "does get_magic_quotes_gpc() return true or false?"
if it returns true, then "$_GET['info_requests_id_rqt'] " is used. if false, then "addslashes($_GET['info_requests_id_rqt']);" is used.
there should be no security concern in php 5.3.8