Sorry for the long silence - I kinda put things on hold for a while (life...). I also decided that trying to keep things going on my old Ubuntu Studio 14.04 is just not viable, it was too broken due to some over-enthusiastic PPA installations...
Anyhow, I re-installed with Ubuntu Studio 15.10, which comes with csound 6.05. The previous build issues have now disappeared, and I can get a rudimentary build going. However, I have noticed two things:
The "getDeps.sh" script tries to install "libjack-dev", which tries to install the old version of Jack (seems that it is not available anymore, current version is libjack-jackd2-dev).
The other thing is that at the end of the build (which seemed to have created a usable "Cabbage" executable nonetheless), I get the following errors (I include the previous couple of lines for context):
../../JuceLibraryCode/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp:272:29: warning: multi-character character constant [-Wmultichar]
setUniqueID ((int) (JucePlugin_VSTUniqueID));
cp: cannot stat ‘./build/CabbageStudio’: No such file or directory
cp: cannot stat ‘../../Images/Cabbage.png’: No such file or directory
I don't see a "CabbageStudio" (was it supposed to be built?), there is only a "Cabbage". Similarly there is no "Cabbage.png" file in "../../Images", but there is a "cabbage.png".
Apart from the above two things, it would appear I have something that can make weird and wonderful sounds. I will try to give it a more in-depth test during the weekend.