add --csv option to nanobench

This makes it trivial to copy/paste into spreadsheets for sorting/diffing

Bug: skia:
Change-Id: I02c920e2b8be8f59270da9fb9bb3e6763987e0bc
Reviewed-on: https://skia-review.googlesource.com/21378
Reviewed-by: Mike Klein <mtklein@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed