sdl3 audio callback

src/Ryujinx.Audio.Backends.SDL3/SDL3AudioBuffer.cs

@@ -0,0 +1,16 @@
+namespace Ryujinx.Audio.Backends.SDL3
+{
+    class SDL3AudioBuffer
+    {
+        public readonly ulong DriverIdentifier;
+        public readonly ulong SampleCount;
+        public ulong SamplePlayed;
+
+        public SDL3AudioBuffer(ulong driverIdentifier, ulong sampleCount)
+        {
+            DriverIdentifier = driverIdentifier;
+            SampleCount = sampleCount;
+            SamplePlayed = 0;
+        }
+    }
+}