fix static relo nondeterminism
fix static relo nondeterminism

Summary: using unordered set for candidates was causing non-deterministic output.

Reviewed By: bertmaher

Differential Revision: D3132205

fb-gh-sync-id: d2ad064cb12b29ba6b38097c2fa87e66a7eeec69
fbshipit-source-id: d2ad064cb12b29ba6b38097c2fa87e66a7eeec69

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex