For those who would give almost anything for a chance at superstardom, “American Idol” might be the entertainment industry’s version of a Faustian bargain: Through 14 seasons, the very successful Fox show has exploited the fact that there are millions of singers who are willing to sign onerous deals for the chance to compete. But season 11 winner Phillip Phillips isn’t going to let the deals he made as a precursor to his fame go unchallenged.