cleanup of c implementation
cleanup of c implementation

pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io,pauldardeau/python-concurrent-disk-io