Move setMixMode to love.audio

src/scripts/boot.lua

@@ -420,10 +420,6 @@ function love.init()
 		love._setGammaCorrect(c.gammacorrect)
 	end
 
-	if love._setAudioMixMode then
-		love._setAudioMixMode(c.audio.mixmode, c.audio.playmuted)
-	end
-
 	-- Gets desired modules.
 	for k,v in ipairs{
 		"thread",
@@ -498,6 +494,10 @@ function love.init()
 		end
 	end
 
+	if love.audio then
+		love.audio.setMixMode(c.audio.mixmode, c.audio.playmuted)
+	end
+
 	-- Our first timestep, because window creation can take some time
 	if love.timer then
 		love.timer.step()