BENNY BLANCO A prodigious talent schools the music business in Hit-making 101         By Michael Gallant Benny Blanco has crafted pop magic in the studio for today’s biggest stars, including Katy Perry, Maroon 5, Rihanna and Bruno Mars. He’s scored more than a dozen No. 1 hits and was named Songwriter of the Year at this year’s BMI Pop Awards. Oh, and he’s 24. That’s an impressive career at any age, but only more so considering its...