optimization for thrift generated code
optimization for thrift generated code

Summary:
I was profiling the cost of deserializing of thrift structures
and this std::move saves some malloc when deserializing sets.

Test Plan: Unittest + my own benchmarking

Reviewed By: alandau@fb.com

Subscribers: trunkagent, marccelani, ruibalp, alandau, mshneer

FB internal diff: D1794047

Tasks: 5806705

Signature: t1:1794047:1421873437:66992bb1f04feb4decde101d05c1655c589140a0

Orvid/fbthrift,chjp2046/fbthrift,chjp2046/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,Orvid/fbthrift,kangkot/fbthrift,sinjar666/fbthrift,facebook/fbthrift,LinusU/fbthrift,HankFaan/fbthrift,getyourguide/fbthrift,HankFaan/fbthrift,sinjar666/fbthrift,LinusU/fbthrift,maxwell-demon/fbthrift,SergeyMakarenko/fbthrift,guker/fbthrift,soumith/fbthrift,chjp2046/fbthrift,soumith/fbthrift,getyourguide/fbthrift,guker/fbthrift,kangkot/fbthrift,maxwell-demon/fbthrift,project-zerus/fbthrift,getyourguide/fbthrift,kangkot/fbthrift,kangkot/fbthrift,guker/fbthrift,project-zerus/fbthrift,guker/fbthrift,HankFaan/fbthrift,kangkot/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,uber/fbthrift,chjp2046/fbthrift,Orvid/fbthrift,raphaelamorim/fbthrift,facebook/fbthrift,HankFaan/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,kangkot/fbthrift,LinusU/fbthrift,uber/fbthrift,fengshao0907/fbthrift,guker/fbthrift,uber/fbthrift,facebook/fbthrift,fengshao0907/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,facebook/fbthrift,kangkot/fbthrift,chjp2046/fbthrift,soumith/fbthrift,LinusU/fbthrift,chjp2046/fbthrift,soumith/fbthrift,getyourguide/fbthrift,uber/fbthrift,project-zerus/fbthrift,project-zerus/fbthrift,LinusU/fbthrift,kangkot/fbthrift,sinjar666/fbthrift,project-zerus/fbthrift,HankFaan/fbthrift,soumith/fbthrift,sinjar666/fbthrift,HankFaan/fbthrift,fengshao0907/fbthrift,soumith/fbthrift,SergeyMakarenko/fbthrift,Orvid/fbthrift,facebook/fbthrift,facebook/fbthrift,uber/fbthrift,maxwell-demon/fbthrift,Orvid/fbthrift,soumith/fbthrift,SergeyMakarenko/fbthrift,maxwell-demon/fbthrift,sinjar666/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,raphaelamorim/fbthrift,fengshao0907/fbthrift,sinjar666/fbthrift,guker/fbthrift,maxwell-demon/fbthrift,LinusU/fbthrift,HankFaan/fbthrift,LinusU/fbthrift,project-zerus/fbthrift,kangkot/fbthrift,uber/fbthrift,LinusU/fbthrift,uber/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,SergeyMakarenko/fbthrift,maxwell-demon/fbthrift,SergeyMakarenko/fbthrift,raphaelamorim/fbthrift,raphaelamorim/fbthrift,maxwell-demon/fbthrift,maxwell-demon/fbthrift,kangkot/fbthrift,SergeyMakarenko/fbthrift,project-zerus/fbthrift,guker/fbthrift,raphaelamorim/fbthrift,sinjar666/fbthrift,HankFaan/fbthrift,chjp2046/fbthrift,HankFaan/fbthrift,fengshao0907/fbthrift,chjp2046/fbthrift,SergeyMakarenko/fbthrift,Orvid/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,HankFaan/fbthrift,Orvid/fbthrift,project-zerus/fbthrift,raphaelamorim/fbthrift,project-zerus/fbthrift,uber/fbthrift,fengshao0907/fbthrift,fengshao0907/fbthrift,soumith/fbthrift,soumith/fbthrift,raphaelamorim/fbthrift,kangkot/fbthrift,sinjar666/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,raphaelamorim/fbthrift,fengshao0907/fbthrift,LinusU/fbthrift,getyourguide/fbthrift,uber/fbthrift,getyourguide/fbthrift,soumith/fbthrift,guker/fbthrift,getyourguide/fbthrift,facebook/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,maxwell-demon/fbthrift,Orvid/fbthrift,Orvid/fbthrift,guker/fbthrift,fengshao0907/fbthrift,soumith/fbthrift,fengshao0907/fbthrift,maxwell-demon/fbthrift,facebook/fbthrift,HankFaan/fbthrift,LinusU/fbthrift,chjp2046/fbthrift,sinjar666/fbthrift,LinusU/fbthrift,fengshao0907/fbthrift,project-zerus/fbthrift,guker/fbthrift,project-zerus/fbthrift,facebook/fbthrift,sinjar666/fbthrift,raphaelamorim/fbthrift,maxwell-demon/fbthrift,getyourguide/fbthrift,project-zerus/fbthrift,guker/fbthrift