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>

apparentlymart/golang,apparentlymart/golang,dsriram/golang,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,dsriram/golang,tv42/old-go,apparentlymart/golang,dsriram/golang,gnanderson/go,dsriram/golang,pombredanne/go-deleteme,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,tv42/old-go,apparentlymart/golang,gnanderson/go,gnanderson/go,pombredanne/go-deleteme,pombredanne/go-deleteme,dsriram/golang,gnanderson/go,gnanderson/go,dsriram/golang,apparentlymart/golang,tv42/old-go,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme