Tim Gray Senior Vice PresidentNetflix’s “Ma Rainey’s Black Bottom” fulfills an idea that was nearly 40 years in the making: a film version of August Wilson’s play.In October 1984, Variety’s Richard Hummler reviewed its Broadway debut, praising Wilson as “a new writer of talent and power.” He added “The play will likely have a healthy production life elsewhere and could make a gripping film.”Three years later, Variety’s Kathleen O’Steen asked Wilson if he would like to see his plays, such as