fast_io.rs: use splice if copy_file_range is not supported - #459

fast_io.rs: use splice if copy_file_range is not supported#459

Franklin-Qi wants to merge 2 commits into

uutils:mainuutils/sed:mainfrom

Franklin-Qi:fix-#443-use-sendfile-or-splice-if-copy-file-range-is-not-supportedFranklin-Qi/sed:fix-#443-use-sendfile-or-splice-if-copy-file-range-is-not-supportedCopy head branch name to clipboard