vim: Import v9.1.1238

* runtime(doc): Add missing garbagecollect() hypertext link
* Improve contributing guide by adding a section on signing off commits
* 9.1.1238: wrong cursor column with 'set splitkeep=screen'
* 9.1.1237: Compile error with C89 compiler in term.c

Author: github-actions[bot]

gitlog.txt

@@ -1 +1 @@
-* [9.1.1236](https://github.com/vim/vim/commit/35cb03648f5e29020a31069d3b6cd997e5608619): tests: test\_comments leaves swapfiles around\n* [9.1.1235](https://github.com/vim/vim/commit/d2232d70c894178b5120d85a42ce8ec9f9dd9d88): cproto files are outdated\n* [9.1.1234](https://github.com/vim/vim/commit/7cedae3ec3be2af24a7e717e4cb4b8658bc4e9b7): Compile error when SIZE\_MAX is not defined\n* [9.1.1233](https://github.com/vim/vim/commit/b42b9fc41f27f92aaf4f96cd4149f3160e9fe588): Coverity warns about NULL pointer when triggering WinResized\n* [runtime(doc): Fix an omission in the documentation.](https://github.com/vim/vim/commit/92e109fc139772727783bc9f3c333e4b346e3ef4)
+* [runtime(doc): Add missing garbagecollect() hypertext link](https://github.com/vim/vim/commit/9d5487f6fdc47760e6bc6ca7beb2d007f2e10066)\n* [Improve contributing guide by adding a section on signing off commits](https://github.com/vim/vim/commit/20e46fa65b98c0e2d47cbb8aef6c9f92a547c504)\n* [9.1.1238](https://github.com/vim/vim/commit/7746348c5d0f4c4707503f856d0335d8921e8d50): wrong cursor column with 'set splitkeep=screen'\n* [9.1.1237](https://github.com/vim/vim/commit/2726821d389e08f8bb5630de1ee2d39ce0f53197): Compile error with C89 compiler in term.c