What do you do when you’re too mature to rock? Linda Ronstadt has recorded pop standards and Mexican songs. Now she more or less combines the styles in an album of Latino pop standards, 11 Afro-Cuban chestnuts from the ’30s, ’40s, and ’50s, plus two new songs from the soundtrack of ”The Mambo Kings.” The music, backed by the Ray Santos Orchestra, is both touching and addictive, so give the lady points for serving it up to her gringo audience. She herself, alas, is tasty only when she sighs or whispers; the strain of singing loudly makes her voice go hard and flat. The album’s title, Frenesi, means ”frenzy,” but Ronstadt barely generates even the slightest heat.