Among the South African players, how many were born before 4/11/1980?
South African players refers to Country_Name = 'South Africa'; born before 4/11/1980 refers to DOB < '1980-4-11'
SELECT SUM(CASE WHEN T1.DOB < '1980-4-11' THEN 1 ELSE 0 END) FROM Player AS T1 INNER JOIN Country AS T2 ON T1.Country_Name = T2.Country_Id WHERE T2.Country_Name = 'South Africa'