Public issue https://github.com/mackron/miniaudio/issues/659

This is set via the engine config.

Smoothing is disabled by default. To enable it, you must use
ma_sound_init_ex() and configure it via the volumeSmoothTimeInPCMFrames
member of ma_sound_config.

This commit also fixes a bug where ma_gainer is not properly applying
smoothing.

This is an attempt to work around an issue with PipeWire.

Public issue https://github.com/mackron/miniaudio/issues/652

This example captures data from the microphone using the low-level API
and then plays back the data through the engine. The intermediary data
source is a ring buffer.

  * ma_engine_get_time_in_pcm_frames() (replaces ma_engine_get_time())
  * ma_engine_get_time_in_milliseconds()
  * ma_engine_set_time_in_pcm_frames() (replaces ma_engine_set_time())
  * ma_engine_set_time_in_milliseconds()

These changes are consistent with the naming of other time based
functions, eliminates ambiguity and just makes it clearer as to what
you're working with.

ma_engine_get_time() and ma_engine_set_time() have been deprecated.

This is not pre-initializing the variable that receives the number of
bytes read to 0 which can result in custom VFS implementations
returning an invalid value if they return early from an error or
whatnot.

Public issue https://github.com/mackron/miniaudio/discussions/647

Note that this does not currently work at runtime.