Don't build benchmarks by default
Don't build benchmarks by default

Summary: There are a number that don't build on OSX or windows, but I missed that in the initial diff. This disables building them for now so we can get contbuilds back into a good state where they can be re-enabled in the future.

Reviewed By: Gownta

Differential Revision: D38520882

fbshipit-source-id: a2910c76241e4ecccf8ca8e56444ee9c35bb5363

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