Fix Savannah bugs #20662, 20688.

Fix Savannah bugs #20662, 20688.
* find/find.c (at_top): Avoid memory leak.
* find/pred.c (do_fprintf, pred_iname, pred_name): Likewise.
(pred_name_common): New function, factored from pred_iname and
pred_name.
* find/parser.c (check_name_arg): Let -nowarn silence -name /.
* locate/locate.c (visit_basename): Avoid memory leak.
* NEWS: Document the changes.
* doc/find.texi (Warning Messages): Document -nowarn's effect on
-name and -iname.
* find/testsuite/find.gnu/name-slash.exp: New test, to ensure
20662 doesn't regress on '-name /', and that 20688 silences the
warning.
* find/testsuite/find.gnu/printf-slash.exp: Likewise.
* find/testsuite/find.gnu/name-slash.xo: Expected results.
* find/testsuite/find.gnu/printf-slash.xo: Likewise.
* find/testsuite/Makefile.am (EXTRA_DIST_XO, EXTRA_DIST_EXP):
Distribute new tests.