x11-fonts/urwfonts-ttf: Do not package fonts.{dir,scale}

They are generated by USES=font post-install. Packaging them just
leads to checksum errors:

Checking for packages with mismatched checksums:
urwfonts-ttf-1.0.7b18_6: /usr/local/share/fonts/urwfonts-ttf/fonts.dir
urwfonts-ttf-1.0.7b18_6: /usr/local/share/fonts/urwfonts-ttf/fonts.scale

PR: 224407
Reported by: Marco Beishuizen <mbeis@xs4all.nl>