bump `rustc-perf` submodule This updates the `rustc-perf` submodule to pull in the recent changes, in particular the error handling in https://github.com/rust-lang/rustc-perf/pull/2021 fixing the error we saw in a recent run. I think I did this correctly, submodules are so annoying. r? kobzol (opening as draft to do a perf run and check that nothing has changed indeed)