Previously the fonts specified in language-selection.sh would override
any specified on the command line.
This changes language-specific.sh from overriding a user request to
just setting the default fonts if none are specified with --fontlist.
The --fontlist argument to tesstrain.sh was always ignored, even if
the language had no specific fonts specified in language-specific.sh.
Change this behaviour so the --fontlist argument is used if no specifc
fonts are selected by language-specific.sh.