audio: Implement a SDL2 backend (#2258)

* audio: Implement a SDL2 backend

This adds support to SDL2 as an audio backend.
It has the same compatibility level as OpenAL without its issues.

I also took the liberty of restructuring the SDL2 code to have one
shared project between audio and input.

The configuration version was also incremented.

* Address gdkchan's comments

* Fix update logic

* Add an heuristic to pick the correct target sample count wanted by the game

* Address gdkchan's comments

* Address Ac_k's comments

* Fix audren output

* Address gdkchan's comments

1 files changed, 16 insertions, 0 deletions

diff --git a/Ryujinx.Audio.Backends.SDL2/SDL2AudioBuffer.cs b/Ryujinx.Audio.Backends.SDL2/SDL2AudioBuffer.cs
new file mode 100644
index 00000000..71ef414a
--- /dev/null
+++ b/Ryujinx.Audio.Backends.SDL2/SDL2AudioBuffer.cs
@@ -0,0 +1,16 @@
+namespace Ryujinx.Audio.Backends.SDL2
+{
+    class SDL2AudioBuffer
+    {
+        public readonly ulong DriverIdentifier;
+        public readonly ulong SampleCount;
+        public ulong SamplePlayed;
+
+        public SDL2AudioBuffer(ulong driverIdentifier, ulong sampleCount)
+        {
+            DriverIdentifier = driverIdentifier;
+            SampleCount = sampleCount;
+            SamplePlayed = 0;
+        }
+    }
+}