CLSA-2026-1778259521 vim: Fix of 4 CVEs

CVE-2022-3278: fix crash when using NUL in buffer that uses :source; don't get a next line when skipping over NL in evalnextnonblank eval.c, upstream patch 9.0.0552 - CVE-2023-48234: fix overflow when getting count for normal z command; break out of nvzet count loop when n LONGMAX/10 normal.c,...