Menus, context menus, toolbars, toolbar items...
could be created with empty names, and could be
renamed to have empty names before this patch.

Change-Id: Ic383f16955746002aa3ad69406bac855cdd58d2d
Reviewed-on: https://gerrit.libreoffice.org/30286Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
Tested-by: Jenkins <ci@libreoffice.org>