Sound (Haiku): add stub file

src/detection/sound/sound_haiku.cpp

@@ -0,0 +1,22 @@
+extern "C"
+{
+#include "sound.h"
+}
+#include <MediaRoster.h>
+
+const char* ffDetectSound(FF_MAYBE_UNUSED FFlist* devices /* List of FFSoundDevice */)
+{
+    BMediaRoster* roster = BMediaRoster::Roster();
+    media_node mediaNode;
+
+    roster->GetAudioOutput(&mediaNode);
+
+    int32_t mediaOutputCount = 0;
+    roster->GetAllOutputsFor(mediaNode, NULL, 0, &mediaOutputCount);
+    if (mediaOutputCount == 0)
+        return NULL;
+
+    // TODO: Implement the rest of the function
+
+    return "Not supported on this platform";
+}