Over more than 50 years as an academic and activist, Marcia Langton has never been known to mince her words. But now the Melbourne University professor, Boyer lecturer, public intellectual and co-author of a landmark report on the Indigenous Voice to parliament and government has really had enough. When Australians go to the polls to vote on the Voice later this year, Langton wants them to think hard about what’s at stake. “I imagine that most Australians who are non-Indigenous, if we lose the ­referendum, will not be able to look me in the eye,” she says. “How are they going to ever ask an I…