The previous "Public domain" is misleading, as we can't assume
such a copyright status when the EXIF info is not set.
<https://translatewiki.net/wiki/Thread:Support/Change_MediaWiki:Exif-copyrighted-false>
Change-Id: Ic471ed5a997b476fd1e8b4a15106ffc8cd895197
'exif-compression-34712' => 'JPEG2000', # only translate this message to other languages if you have to change it
'exif-copyrighted-true' => 'Copyrighted',
-'exif-copyrighted-false' => 'Public domain',
+'exif-copyrighted-false' => 'Copyright status not set',
'exif-photometricinterpretation-2' => 'RGB', # only translate this message to other languages if you have to change it
'exif-photometricinterpretation-6' => 'YCbCr', # only translate this message to other languages if you have to change it