testing: increase benchmark output to four significant figures
Currently, the benchmark output from the testing package prints small
values with three significant figures. This means it can only
distinguish 1 part in 100, or a 1% error, which can be enough to throw
off further analysis of the output. This CL increases it to four
significant figures. For time values, at least, anything beyond four
significant figures is almost certainly noise.
Fixes #34626.
Change-Id: I3bcf305427130026276e6a4c78167989319f280c
Reviewed-on: https://go-review.googlesource.com/c/go/+/267102
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>