Merge branch 'master' into core-updates

build: Update PO files as per 'make dist'.

nls: Update 'eo' and 'vi' translations.

nls: Remove obsolete messages from PO files.

Suggested by Benno Schulenberg <coordinator@translationproject.org>.

* po/guix/eo.po, po/guix/pt_BR.po, po/guix/sr.po, po/guix/vi.po,
  po/packages/eo.po, po/packages/pt_BR.po, po/packages/sr.po,
  po/packages/vi.po: Remove obsolete messages.

Merge branch 'master' into core-updates

Update '.po' files.

Update '.po' files.

nls: Add Vietnamese translation.

* po/vi.po: New file.
* po/LINGUAS: Add 'vi'.