testing/ardour-6.5.0: build failures

After the upgrade to ardour-6.5.0, it fails to build with many errors, for example:

../libs/vst3/pluginterfaces/base/funknown.h:363:2: error: 'PLUGIN_API' declared as a 'virtual' field
  363 |  virtual tresult PLUGIN_API queryInterface (const TUID _iid, void** obj) = 0;
      |  ^~~~~~~
../libs/vst3/pluginterfaces/base/funknown.h:363:18: error: expected ';' at end of member declaration
  363 |  virtual tresult PLUGIN_API queryInterface (const TUID _iid, void** obj) = 0;
      |                  ^~~~~~~~~~
      |                            ;
../libs/vst3/pluginterfaces/base/funknown.h:363:29: error: ISO C++ forbids declaration of 'queryInterface' with no type [-fpermissive]
  363 |  virtual tresult PLUGIN_API queryInterface (const TUID _iid, void** obj) = 0;
      |                             ^~~~~~~~~~~~~~
../libs/vst3/pluginterfaces/base/funknown.h:368:2: error: 'PLUGIN_API' declared as a 'virtual' field
  368 |  virtual uint32 PLUGIN_API addRef () = 0;
      |  ^~~~~~~
../libs/vst3/pluginterfaces/base/funknown.h:368:17: error: expected ';' at end of member declaration
  368 |  virtual uint32 PLUGIN_API addRef () = 0;
      |                 ^~~~~~~~~~
      |                           ;

See: https://build.alpinelinux.org/buildlogs/build-edge-armhf/testing/ardour/ardour-6.5.0-r0.log

The package has been disabled for the time being.