CVE-2026-34982: Vim modeline bypass via various options affects Vim < 9.2.0276

Vim is an open source, command line text editor. Prior to version 9.2.0276, a modeline sandbox bypass in Vim allows arbitrary OS command execution when a user opens a crafted file. The `complete`, `guitabtooltip` and `printheader` options are missing the `P_MLE` flag, allowing a modeline to be executed. Additionally, the `mapset()` function lacks a `check_secure()` call, allowing it to be abused from sandboxed expressions. Commit 9.2.0276 fixes the issue.