CVE-2026-6368: posix: make wordexp work on a copy of we_wordv when
WRDE_APPEND is set and restore the original on non-NOSPACE errors,
preventing a use-after-free in wordfree; add tst-wordexp-append
regression test
CVE-2026-77117: iconvdata: clear the pending character in the
SHIFT_JISX0213 decoder after emitting it, preventing an infinite
conversion loop
CVE-2026-19542: misc: use a fixed-size node stack with bounds asserts in
tdelete to fix an out-of-bounds stack write during rebalancing