Sign language interpreters swung their hips and gestured at deaf audience members to the rhythm of a rollicking performance by drag queens singing and dancing on stage behind them. Nothing surprising for a Broadway show, except this is China.  The Tony award-winning musical “Kinky Boots” has broken new ground in the socially conservative nation. The show has filled theaters in Beijing, Shanghai and Guangzhou, lighting up audiences in a country where LGBT-themed entertainment is often censored and rarely gets major — if any — billing. It also has reached a broader audience than usual in China: “Kinky Boots” was the first musical to offer sign language interpreters for the hearing-impaired in the country.