aaudio: Respect SDL_HINT_AUDIO_DEVICE_STREAM_ROLE hint.

Fixes #15299.

include/SDL3/SDL_hints.h

@@ -402,6 +402,11 @@ extern "C" {
  * - "Movie" - Music or sound with dialog
  * - "Media" - Music or sound without dialog
  *
+ * Android's AAudio target supports this hint as of SDL 3.4.4. Android does
+ * not support the exact same options as WASAPI, but for portability, will
+ * attempt to map these same strings to the `aaudio_usage_t` constants. For
+ * example, "Movie" and "Media" will both map to `AAUDIO_USAGE_MEDIA`, etc.
+ *
  * If your application applies its own echo cancellation, gain control, and
  * noise reduction it should also set SDL_HINT_AUDIO_DEVICE_RAW_STREAM.
  *