“Nightcrawler,” the aptly titled directing debut of veteran Hollywood screenwriter Dan Gilroy, may be a little too sleazy and knowing for its own good. After watching Jake Gyllenhaal’s intense and unsettling performance as a sociopathic TV news cameraman chasing the most gruesome late-night stories across Los Angeles, you may need a shower, a Valium and a triple shot of whiskey, without feeling entirely sure you want to wake up the next day.