The Barbican Music Library is celebrating British pop culture with a show that features Mel B’s leopard catsuit, Emma Bunton’s blue dress and Geri Halliwell’s Union Jack boots The Spice Girls performed at the Brit Awards in 1997. JMEnternational / Redferns / Getty Images In 1996, Great Britain succumbed to “ Spicemania .” The Spice Girls’ first album,  Spice , broke sales records when it debuted that November, instantly cementing the girl group as pop royalty. Thirty years later, items worn by the band’s members are the highlight of a new exhibition celebrating what its curator calls the “wildest year of Britain’s wildest decade.” Now on display at the Barbican Music Library in London, the celebration of “ Cool Britannia ” looks back at the music, fashion, sports and art that made 1996 a banner year in British pop culture.…