Cast an unused variable to void
Cast an unused variable to void

Summary:
This variable seems to be left around for debugging purposes, so just
cast it to void here so that clang13 doesn't Werror out.

Reviewed By: smeenai

Differential Revision: D29721435

fbshipit-source-id: 917f278c29b807106c2660b20deb2b78fe38b47a

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