add missing destructor guard around pipeline
add missing destructor guard around pipeline

Summary: Missing destructor guard causing ASAN failures if read and write failure happen in the same eventloop, i.e. if writes are pending and we get EOF.

Test Plan:
fbconfig --sanitize=address servicerouter/client/cpp2/test:secodarytest
fbmake runtests

no ASAN failures - I do see (unrelated?) failures in secondary test though

Reviewed By: alandau@fb.com

Subscribers: doug, alandau, bmatheny, mshneer, yfeldblum

FB internal diff: D1948800

Signature: t1:1948800:1427474608:28c300c39eb6f9fa20aec9ea5a037c824c10448d

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