Prefer CPU time (when available) for benchmarks.
Prefer CPU time (when available) for benchmarks.

Change-Id: Iaef04f155fb3bfa35b0945e7fd003f1343fdf34f
Reviewed-on: https://code-review.googlesource.com/5164
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

google/re2,google/re2,google/re2,google/re2,google/re2