chown: work around symlink issues on odd platforms Problem reported by Jordi Sanfeliu in: https://lists.gnu.org/archive/html/bug-gnulib/2023-07/msg00116.html * lib/chown.c (rpl_chown) [CHOWN_MODIFIES_SYMLINK]: Do not declare unused locals st, stat_valid. Redo to just call chown if arg is a symlink. This induces a race but is perhaps the best we can do easily on oddball platforms where chown does not follow symlinks.