NEW YORK – For Steve McQueen, bringing back the London of his childhood began with remembering the scents of his youth.In “Small Axe,” McQueen’s ambitious five-film anthology about London’s West Indian community, the “12 Years a Slave” director resurrects the British capital in the decades before its multicultural present, tracing the Caribbean immigrant experience through the racism of the ’60s, ’70s, and ’80s in order to illuminate the injustices of today.