The fontconfig initialisation hardcodes using Arial. However it may
not be available, whereas the fonts being used later will be, so use
one of them for initialisation instead.
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.
