remove unused stat tracking from SkArenaAlloc

I'm really only trying to remove the dependency on SkDebugf().
If we want to keep this, I could switch it to take an optional
stats callback called in the destructor?

Change-Id: I5aa2a58ccc7c8e17e61f29b482b2851be056fa07
Reviewed-on: https://skia-review.googlesource.com/132922
Auto-Submit: Mike Klein <mtklein@chromium.org>
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
2 files changed