io.c: use copy_file_range() if defined
configure.ac: check copy_file_range()
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: use copy_file_range() if defined
configure.ac: check copy_file_range()
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e