Simplify some optional uses and lambdas in MainRunner
Simplify some optional uses and lambdas in MainRunner

Reviewed By: styurin

fbshipit-source-id: 47ff8d3e56

JoelMarcey/buck,romanoid/buck,Addepar/buck,Addepar/buck,Addepar/buck,romanoid/buck,romanoid/buck,zpao/buck,romanoid/buck,Addepar/buck,kageiit/buck,nguyentruongtho/buck,romanoid/buck,romanoid/buck,zpao/buck,romanoid/buck,Addepar/buck,facebook/buck,JoelMarcey/buck,JoelMarcey/buck,kageiit/buck,JoelMarcey/buck,JoelMarcey/buck,kageiit/buck,zpao/buck,romanoid/buck,JoelMarcey/buck,nguyentruongtho/buck,kageiit/buck,facebook/buck,kageiit/buck,zpao/buck,romanoid/buck,JoelMarcey/buck,zpao/buck,romanoid/buck,JoelMarcey/buck,kageiit/buck,nguyentruongtho/buck,nguyentruongtho/buck,JoelMarcey/buck,zpao/buck,nguyentruongtho/buck,Addepar/buck,facebook/buck,Addepar/buck,Addepar/buck,romanoid/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,Addepar/buck,romanoid/buck,Addepar/buck,facebook/buck,romanoid/buck,nguyentruongtho/buck,nguyentruongtho/buck,facebook/buck,Addepar/buck,kageiit/buck,facebook/buck,facebook/buck,zpao/buck,Addepar/buck,Addepar/buck