bug#53591: Audacity can't find FFmpeg

[Leo Famulari]

On Thu, Jan 27, 2022 at 06:14:30PM -0500, Leo Famulari wrote:
> Although Audacity 3.1.3 includes FFmpeg in its direct dependencies, it
> does not keep a reference to it and cannot find it at runtime.

One consequence is that Audacity can't read Ogg files containing Opus or
Vorbis audio, or any other format delegated to FFmpeg, for example, this
file:

https://dl.espressif.com/dl/audio/ff-16b-2c-44100hz.ogg <-- downloads
with an ".ogx" extension

VLC, on the other hand, plays it fine.

Testing with the previous version of audacity (2.4.2), the .ogx file is
opened using FFmpeg, as shown in the "opening..." progress dialog box.