CLSA-2026-1777444367 vim: Fix of 9 CVEs

CVE-2021-3903: do not set VALIDBOTLINE in wvalid when the screen is not valid, preventing invalid memory access while scrolling. - CVE-2021-4069: copy the current line before regexec in exopen so the match is not using freed memory when searching for a mark flushes it. - CVE-2022-0351: limit...