Fix Pulse Audio Issues

[iyoko]

Got this email, need to look into fixing it!

"""
I tried to configure cursynth with the --with-pulse option, and encountered some problems. Firstly, the rtmidi subpackage does not support pulseaudio, so an alsa (or other) library also needs to be available. Also, the libraries dependencies are not passed back to the cursynth configuration, so that when linking the cursynth binary the libraries needed by rtmidi are not included. This can be overcome by, e.g. using LDFLAGS="-lasound" together with --with-pulse when configuring.

After successfully building with the workarounds mentioned above, however, the cursynth executable exits with the following error:

RtApiPulse::probeDeviceOpen: unsupported sample format.

Examining the cursynth source, I see in cursynth.cpp on line 309, that it's trying to open an rtaudio stream with the RTAUDIO_FLOAT64 sample format, which is unfortunately not supported from the rtaudio pulseaudio interface. I tried changing the FLOAT64 to FLOAT32, but ran into an assertion error in pulseaudio it seems.
"""