[CWB] more on OS X build issues

[Hardie, Andrew]

Sorry for the 3 list posts in quick succession but I've just noticed this comment in config/platform/darwin-64 :

## Only build default 64-bit architecture (since homebrew's universal glib build is broken for latest glib 2.30.2)
(by Stefan on Feb 19th this year)

Stefan, do you think this might be linked to the issues Josep has been encountering? 

Meta comment: is building on OS X problematic for others? If so, we should prob have binaries of the 3.4 trunk for download on sf.net.

Andrew.