benchmark: include all compression levels in benchmarks

This changes the JSON format and breaks the HTML output, and it
wouldn't handle all the additional data well, so it has been removed.
The current plan is to rewrite that code using d3.js/NVD3.  Progress
(or lack thereof) on the rewrite is being tracked at
https://github.com/quixdb/squash/issues/57

Signed-off-by: Evan Nemerson <evan@coeus-group.com>
build: remove vestigial components

Signed-off-by: Evan Nemerson <evan@coeus-group.com>