Fix bench compilation error.
Fix bench compilation error.

Add 'extern crate test' removed by mistake in 93954f697baa50df2f010da54acb9d825082d15c.

asantopietro/racer,pmarcelll/racer,racer-rust/racer,rranelli/racer,phildawes/racer,drewet/racer,drewet/racer,BonsaiDen/racer,andelf/racer,ifraixedes/racer,MattWis/racer,asantopietro/racer,alkama/racer,Wilfred/racer,syhkiller/racer,sliz1/racer,syhkiller/racer,ane/racer,syohex/racer,syohex/racer,ajroetker/racer,kbknapp/racer,kbknapp/racer,dleslie/racer,sthapaun/racer,rranelli/racer,bluss/racer,bluss/racer,hotpxl/racer,MattWis/racer,birkenfeld/racer,BonsaiDen/racer,ane/racer,sthapaun/racer,ifraixedes/racer,jaxx/racer,ajroetker/racer