OSX failing

All OSX builds are failing with rts/Linker.c:6371:1: error: error: unused function 'machoGetMisalignment' [-Werror,-Wunused-function] See eg https://phabricator.haskell.org/harbormaster/build/14551/ So I get lots of “Phab failed” messages, and am now simply deleting them, which rather defeats the object of the exercise. Could someone fix this, or (I suppose) switch off the OSX build? Simon