Profanity use predating Gone With the Wind by six years.
In the scene where the senior Marryot and his surviving adult son are conversing and sharing a drink, the father uses the words "damn" and "hell;” the son also says "hell."
I don't believe this is the first talking picture to use such words, as I know of at least one other, a Western from 1929-30 starring Charles Bickford, which also employs mild profanity at least once. Still, for aficiandos of film lore, I'm offering at least one specific example in Hollywood cinema which shatters the myth that GWTW was the first to break the profanity barrier when Clark Gable, as Rhett Butler, utters "Frankly, my dear, I don't give a damn!"
Okay folks, show's over, nothing to see here!