Miniaudio

- Fix the C++ build.

- WASAPI: Fix a bug where a result code is not getting checked at initialization time.
- WASAPI: Bug fixes for loopback mode.
- ALSA: Fix a possible deadlock when stopping devices.
- Mark devices as default on the null backend.

- Core Audio: Fix a memory leak.
- Core Audio: Fix a bug where the performance profile is not being used by playback devices.
- JACK: Fix loading of 64-bit JACK on Windows.
- Fix a calculation error and add a safety check to the following APIs to prevent a division by zero:
- ma_calculate_buffer_size_in_milliseconds_from_frames()
- ma_calculate_buffer_size_in_frames_from_milliseconds()
- Fix compilation errors relating to c89atomic.
- Update FLAC decoder.

- WASAPI: Fix a deadlock in exclusive mode.
- WASAPI: No longer return an error from ma_context_get_device_info() when an exclusive mode format
cannot be retrieved.
- WASAPI: Attempt to fix some bugs with device uninitialization.
- PulseAudio: Yet another refactor, this time to remove the dependency on `pa_threaded_mainloop`.
- Web Audio: Fix a bug on Chrome and any other browser using the same engine.
- Web Audio: Automatically start the device on some user input if the device has been started. This
is to work around Google's policy of not starting audio if no user input has yet been performed.
- Fix a bug where thread handles are not being freed.
- Fix some static analysis warnings in FLAC, WAV and MP3 decoders.
- Fix a warning due to referencing _MSC_VER when it is undefined.
- Update to latest version of c89atomic.
- Internal refactoring to migrate over to the new backend callback system for the following backends:
- PulseAudio
- ALSA
- Core Audio
- AAudio
- OpenSL|ES
- OSS
- audio(4)
- sndio

- Make some functions const correct.
- Update ma_data_source_read_pcm_frames() to initialize pFramesRead to 0 for safety.
- Add the MA_ATOMIC annotation for use with variables that should be used atomically and remove unnecessary volatile qualifiers.
- Add support for enabling only specific backends at compile time. This is the reverse of the pre-existing system. With the new
system, all backends are first disabled with `MA_ENABLE_ONLY_SPECIFIC_BACKENDS`, which is then followed with `MA_ENABLE_*`. The
old system where you disable backends with `MA_NO_*` still exists and is still the default.

- Fix a crash in ma_audio_buffer_read_pcm_frames().
- Update spinlock APIs to take a volatile parameter as input.
- Silence some unused parameter warnings.
- Fix a warning on GCC when compiling as C++.