Cancel file descriptors when closing. kpoll_destory now takes a 'closefd' function to be used to close file descriptors
Cancel file descriptors when closing. kpoll_destory now takes a 'closefd' function to be used to close file descriptors

As suggested in https://github.com/wahern/cqueues/pull/174#issuecomment-266173627

wahern/cqueues,wahern/cqueues