No OOM in dict_alloc() and rettv_dict_alloc()
No OOM in dictitem_alloc()
No OOM in hash_may_resize() and hash_add_item()

hash_add() can still return FAIL if the key already exists.
No OOM in dictitem_copy
No OOM in listitem_alloc()
No OOM in list_insert_tv() and list_extend()
No OOM in save_cmdline_alloc()
No OOM in autoload_name()
No OOM in expand_shellcmd()
No OOM in ExpandGeneric()
do_map() won't return 4 (OOM) anymore
No OOM in msg_show_console_dialog()
au_get_grouparg() can't fail, remove error handling
No OOM in popup_mode_name()
No OOM in vim_strnsave_up()

And some cleanup in strsave_up()
No OOM in vim_strsave_escaped[_ext]()
No OOM in enc_canonize()

Fix a `return FAIL` that should be `return NULL` in `enc_locale()`
No OOM in vim_strsave_fnameescape()
No OOM in home_replace_save()
No OOM in vim_strsave_escape_csi()