libtoolize: don't remove install-sh.

If you are not using automake, libtoolize would remove install-sh.
It needs the same treatment as config.guess and config.sub.
* libtoolize.in (func_require_seen_libtool): Remove install-sh
from $all_pkgaux_files, the list of files removed by
`libtoolize --force`.
* THANKS: Add Todd C. Miller.
* NEWS: Update.

Copyright-paperwork-exempt: Yes
Signed-off-by: Gary V. Vaughan <gary@gnu.org>