Most of these scripts can probably just be deleted (see issue #2045),
but for now it was easier to just mechanically fix the shellcheck
warnings in them, rather than think about whether we actually needed the
script.
Fixes done using shellcheck 0.7.0 with default options. I haven’t tested
any of the changes.
Signed-off-by: Philip Withnall <withnall@endlessm.com>