testing: fix bogus benchmark Fatal must not be called from secondary goroutines. Fixes issue 7401.
testing: fix bogus benchmark
Fatal must not be called from secondary goroutines.
Fixes issue 7401.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/67820047

apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang