Add compression level 0 for Brotli

[joliss]

Brotli has a compression level 0 (brotli -q 0) that is even faster than level 1, but the benchmark dataset only seems to have Brotli levels 1 through 11. Perhaps this is worth adding?

I looked at the source to see if I could send a pull request, but I only found this line and this line, which both seem to indicate that the Brotli levels should already go from 0 to 11. So I must be misreading something.