Fix OSS build
Fix OSS build

Summary:
gcc 4.9 cannot infer the `<<` operand overloading the way we expected.
I tried different code arrangements, but it just doesn't pick up. I'm fine with removing the tracing code from the repo.

Reviewed By: int3

Differential Revision: D13976852

fbshipit-source-id: 2f422bab65fcab061815fa5124db45ee32e782f4

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