Currently the emacs ignore patterns include `**/.#*` (lock files), but
doesn't include `**/#*#` (autosave files;
https://www.emacswiki.org/emacs/AutoSave, not to be confused with
`**/*~` backup files which are ignored.)
Add autosave files.
When creating files in Go, the stdlib will create (and then rapidly
delete) files ending with `-go-tmp-umask` to determine the umask
to use for permission purposes.
This can cause trouble with Live Update because the files tend to
vanish underneath it, for example.
Fixes#5117.