vim: Import v9.1.1818

* 9.1.1818: possible crash when calculating topline in diff.c

Author: github-actions[bot]

gitlog.txt

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-* [Filelist: include nsis/icons/README.txt](https://github.com/vim/vim/commit/34959362b6eed61be0069878df6e4712409f25bf)\n* [runtime(doc): Clarify use of "noselect" in 'completeopt'](https://github.com/vim/vim/commit/cfcf1a57cbef90831c26626aee6ba9491fb85cb3)\n* [runtime(vim): Update base syntax, contain user command replacement text](https://github.com/vim/vim/commit/0977c8b03e7eca56bb640acd2fd1c6f5fc825899)\n* [runtime(optwin): Update formatting of option descriptions](https://github.com/vim/vim/commit/a644b7924dbfa42248d563f268b608003474e6eb)\n* [9.1.1817](https://github.com/vim/vim/commit/e3ed5584ed7fad7070d49ddfba4f41bc2b22ca97): popup: there are some position logic bugs\n* [nsis: Rework icons, update icons archive, add copyright notice](https://github.com/vim/vim/commit/c7b2dcd986cd2f392c38825170c9086eee4b6552)\n* [rutnime(new-tutor): Updated English new tutor](https://github.com/vim/vim/commit/9d57fe278f71117414956a33c9beb1407c420ae2)\n* [runtime(doc): Tweak documentation style](https://github.com/vim/vim/commit/6e282117c7409af15f33120e67a00c47eefbbba5)\n* [9.1.1816](https://github.com/vim/vim/commit/55653887adf3892ba46704367e78724187d7b06b): existing icon files are dated\n* [runtime(netrw): MS-Windows: fix netrw not being able to navigate to parent folder](https://github.com/vim/vim/commit/8337d77effac6b556a4db1f5dd9f722c48e38a59)\n* [runtime(doc): make :h virtcol() more accurate](https://github.com/vim/vim/commit/014c731fa50c28c94d56545938b6a05a86234c30)
+* [9.1.1818](https://github.com/vim/vim/commit/d32b3bb7ebe29f856a054cfd552c68afabd065c3): possible crash when calculating topline in diff.c