portaudio 19.20210406-2

[Takashi Yano]

The following packages have been uploaded to the Cygwin distribution:

* libportaudio2-19.20210406-2
* libportaudiocpp0-19.20210406-2
* libportaudio-devel-19.20210406-2
* libportaudiocpp-devel-19.20210406-2

PortAudio is a free, cross platform, open-source, audio I/O
library.  It lets you write simple audio programs in C that will compile and
run on many platforms including Windows, Macintosh (8,9,X), Unix (OSS), SGI,
and BeOS. PortAudio is intended to promote the exchange of audio synthesis
software between developers on different platforms.

- Drop win32 backends because all of them in 19.20210406-1 do not work
  properly for unknown reason. Instead, use OSS in 19.20210406-2.