build(vim-patch): misc n/a funcs, headers, err msgs #41116

* build(vim-patch): n/a func in version.c

init_longVersion() sets datetime for ":version".
Nvim removed it for more deterministic builds.

* build(vim-patch): n/a header from amiga

* build(vim-patch): n/a vim9 err msg for declaring vars

* build(vim-patch): nvim support.txt replaces *os-support*

* build(vim-patch): vim xdg is n/a

* build(vim-patch): n/a 1-line err msg

Vim error message can be 1-line (globals.h), not multi-line (errors.h).
Target v8.2.1032

scripts/vim_na_hunks_vim.txt

@@ -96,6 +96,7 @@
 \*builtin-function-list\*
 \*emacs[_-]tags\*
 \*help-toc-install\*
+\*os-support\*
 \*patches-\(after-\)\?[0-9].*\*
 \*test_gui_[a-zA-Z0-9_]\+()\*
 \*v:none\*