fix up r319744, add new files
8269 dtrace stddev aggregation is normalized incorrectly
illumos/illumos-gate@79809f9cf402f130667349b2d4007ecd65d63c6f
https://github.com/illumos/illumos-gate/commit/79809f9cf402f130667349b2d4007ecd65d63c6f
https://www.illumos.org/issues/8269
It seems that currently normalization of stddev aggregation is done incorrectly. We divide both the sum of values and the sum of their squares by the normalization factor. But we should divide the sum of squares by the normalization factor squared to scale the original values properly.
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Andriy Gapon <avg@FreeBSD.org>