Sync from coreutils.

Sync from coreutils.

Avoid the double-free (first in fts_read, second in fts_close) that
would occur when an `active' directory is made inaccessible (e.g.,
via chmod a-x) during a traversal.
* lib/fts.c (fts_read): After a failed fchdir, update sp->fts_cur
before returning.  Reproduce this failure by
mkdir -p a/b; cd a; chmod a-x . b

* lib/sha1.c: Tweak grammar in a comment.
* m4/fpending.m4: Also include <stdio.h>, for Dragonfly.

* m4/memcoll.m4 (gl_MEMCOLL): Don't require AC_FUNC_MEMCMP, undoing
the 2002-12-31 change.