Updated runtime files.
https://github.com/vim/vim/commit/acb4f221c715a333f4c49a2235a8006c6ac6e4d5
Ignored changes to:
* doc/eval.txt since alloc_fail isn't relevant for neovim
* doc/index.txt for unmerge :smile command
* doc/tags, syntax/vim.vim since they're generated at build time
* doc/todo.txt
