runtime: add benchmark for complex128 division
runtime: add benchmark for complex128 division

R=golang-dev, dave, rsc
CC=golang-dev, minux.ma
http://codereview.appspot.com/6070043

Committer: Dave Cheney <bfcdf3e6ca6cef45543bfbb57509c92aec9a39fb@cheney.net>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go