only warn if fontfile load fails
only warn if fontfile load fails

since it can fail for things like adding the same font twice from
different files

thanks molfar

see https://github.com/libvips/libvips/issues/2220

jcupitt/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips,lovell/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips