The National, Modest Mouse, Edward Sharpe & The Magnetic Zeros, Spoon, Local Natives, The Gaslight Anthem, Portugal The Man and Violent Femmes are among the acts that will appear at the Shaky Knees Mu. MUMBAI: Manipuri folk singer Mangka has joined hands with Portuguese group ‘Cla’ for a song, proceeds from which are being donated to a foundation that helps carry out wishes of children with degenerative diseases. She and…