Update SDL2 to the latest commit (85bbf8e)

libs/SDL2/include/SDL_audio.h

@@ -500,9 +500,7 @@ extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
  * hardware.
  *
  * `spec` will be filled with the sample rate, sample format, and channel
- * count. All other values in the structure are filled with 0. When the
- * supported struct members are 0, SDL was unable to get the property from the
- * backend.
+ * count.
  *
  * \param index the index of the audio device; valid values range from 0 to
  *              SDL_GetNumAudioDevices() - 1
@@ -586,6 +584,7 @@ extern DECLSPEC int SDLCALL SDL_GetAudioDeviceSpec(int index,
  * - `SDL_AUDIO_ALLOW_FREQUENCY_CHANGE`
  * - `SDL_AUDIO_ALLOW_FORMAT_CHANGE`
  * - `SDL_AUDIO_ALLOW_CHANNELS_CHANGE`
+ * - `SDL_AUDIO_ALLOW_SAMPLES_CHANGE`
  * - `SDL_AUDIO_ALLOW_ANY_CHANGE`
  *
  * These flags specify how SDL should behave when a device cannot offer a