I don't know if the government of any African country have adopted the system of paying salaries in Bitcoin,
No African country has announced the full adoption of Bitcoin as legal tender aside the central Africa republic who is the only country in Africa that have adopted Bitcoin as an alternative and even at that, they have not made it known whether or not Bitcoin is used as an official currency for workers salaries, although we already are aware of the sceptical nature of many governments towards bitcoin and many of the countries have been on attacking mode and the majority give a red light to Bitcoin adoption.
So for that, we are still far from achieving that state where an African country will adopt Bitcoin to pay salary, and not even El Salvador who was the first country to adopt Bitcoin has not implemented that law in its system yet.