CLSA-2026-1774363216 vim: Fix of 3 CVEs

CVE-2026-28420: fix heap-buffer-overflow in :terminal when processing Unicode combining characters from supplementary planes - CVE-2026-28418: fix OOB read in Emacs tags parsing with overlong tag file - CVE-2026-28419: fix heap-buffer-underflow in Emacs tags parsing when delimiter appears at...