bug#68439: icewm do not install MO files.

[Feng Shu]

Hello:

At the moment: icewm do not install MO files to
'share/locale/<lang>/LC_MESSAGES', gmo files in tarball are removed, but
do not re-generated, I try to add gettext-minimul to inputs, but can not
re-generate gmo files successfully.

Any reason we should remove gmo files in tarball?

```
               (add-after 'unpack 'remove-gmo-files
                 ;; gmo files are generated from .po files
                 ;; so remove them before build to make sure
                 ;; they are re-generated if needed
                 (lambda _
                   (for-each delete-file
                             (find-files "po" "\\.gmo$"))))
```


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