Fixing crashes
Fixing crashes

Summary:
The fix in header client channel prevents the situation when both saslError and saslComplete
are called in same EventBase iteration.

Test Plan: unit tests

Reviewed By: andrei.bajenov@fb.com

Subscribers: trunkagent, mcduff, marccelani, hitesh, alandau, bmatheny, mshneer

FB internal diff: D1634188

Tasks: 5388156

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