Hopefully this makes it more clear which stats are subsets of others,
and which ones should add up to other ones.

ex it was easy to think that "rewriter_attempts" succeeded as long
as "rewriter_aborts" didn't get incremented, but it could also not
have gotten started, etc.

Here's an example of the new stats:
ic_attempts: 1724625
ic_attempts_nopatch: 1306007
ic_attempts_skipped: 404969
ic_attempts_skipped_megamorphic: 85558
ic_attempts_successful: 13649
ic_rewrites: 13649
ic_rewrites_aborted: 3248
ic_rewrites_aborted_assemblyfail: 65
ic_rewrites_committed: 10401