fchownat: improve on test failure fix * lib/fchownat.c (rpl_fchownat): Clear the flag only if the trailing slash check needs to be made. Do this before checking for the nofollow bug, to avoid the need for the fork+chdir+lchown dance in that case. Move the empty-filename check earlier, so that its file[0] check can more easily be combined with the trailing slash check. * m4/chown.m4, m4/fchownat.m4, modules/fchownat: Revert most recent change.