CLSA-2026-1791894819 glibc: Fix of 8 CVEs

CVE-2026-6368: posix: make wordexp work on a copy of wewordv when WRDEAPPEND 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 SHIFTJISX0213 decoder...