comparisons should include "summary" numbers

[nikomatsakis]

I would like it if comparisons included the "summary", "summary-check", and "summary-opt" numbers. It's very hard right now to get a kind of "overall" picture. Once we make more progress on established benchmark suites (i.e., for the scenarios in rust-lang/rust#48547), then I would want those included (I'm assuming those would replace the "summary" numbers anyway).

[nikomatsakis]

The other thing I wanted is to be able to see the effects for "all clean builds", "all println builds", etc. This comes back to the suites that @michaelwoerister laid out, I suppose.