CLSA-2025-1737024110 vim: Fix of CVE-2021-3903

CVE-2021-3903: fix invalid memory access when scrolling without valid screen...

Fix of CVE: CVE-2021-3875, CVE-2021-3872, CVE-2021-3903

CVE-2021-3872: fix illegal memory access if buffer name is very long - CVE-2021-3875: fix mlget error after search with range - CVE-2021-3903: fix invalid memory access when scrolling without a valid screen...