Added comments clarifying Device::nextWorkItem() operation.
Added comments clarifying Device::nextWorkItem() operation.

mpflanzer/Oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind,mpflanzer/Oclgrind,bitfusionio/Oclgrind,surround-io/oclgrind,surround-io/oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,surround-io/oclgrind,bitfusionio/Oclgrind,bitfusionio/Oclgrind