[autofit] Add support for Tai Viet script. * src/autofit/afblue.dat: Add blue zone data for Tai Viet. * src/autofit/afblue.c, src/autofit/afblue.h: Regenerated. * src/autofit/afscript.h: Add Tai Viet standard characters. * src/autofit/afranges.c, src/autofit/afstyles.h: Add Tai Viet data.