readded custom barrier class, linker errors

specifically the function calls to barrier_init, barrier_wait
and barrier_destory are not being linked properly
moved updateAngles outside of for loop

was previously updating angles on each iteration across the audioObjects,
though a single call to updateAngles updates angles for all audio objects
fixed linker errors related to barrier functions

implemented the proposed fix in this SO thread: http://stackoverflow.com/a/7376015/1402368