Suffering from post-election with drawl? Jay Leno has John McCain on tonight (11:35 p.m., NBC, A).Letterman gets snubbed again.No surprise McCain chose Leno over David Letterman to re-appear in public. After ditching Dave when the economy went south, the Arizona senator flamed out in that last, desperate, pre-election Letterman appearance. His well rehearsed “I screwed