Windows tests don't compile (unknown type name ‘IXAudio27SourceVoice’)

[alexhenrie]

The README says to run make faudio_tests.exe to cross-compile the Windows tests, but when I do that I get:

x86_64-w64-mingw32-gcc -g -Wall -Wall -I/usr/include/wine/windows/ -o faudio_tests.exe xaudio2.c -lole32
xaudio2.c:185:5: error: unknown type name ‘IXAudio27SourceVoice’
  185 |     IXAudio27SourceVoice *xa27src;
      |     ^~~~~~~~~~~~~~~~~~~~

Since commit 14c44d0b0a2 ("xaudio2: Use the preprocessor to modify definitions in xaudio2.idl and xaudio2fx.idl", 2023-04-24), Wine doesn't have an interface named IXAudio27SourceVoice, and as far as I can tell, Windows never had one.