The dive-bombing guitar riffs of The Smiths' 1984 classic “How Soon Is Now?” would have sufficed for Johnny Marr to achieve alt-rock immortality. But the Manchester native is a restless creative soul who has co-written with The The and Kirsty MacColl, forged a synth-driven path with the early-’90s band Electronic, pushed indie-rock titans Modest Mouse to new heights in the 2000s, and developed an earnest solo catalogue.