[te] Make BUILD_TENSOREXPR_BENCHMARK a real CMake option (#48158)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/48158
Test Plan: Imported from OSS
Reviewed By: Chillee
Differential Revision: D25059877
Pulled By: bertmaher
fbshipit-source-id: a98b6c18a91b4fe89d12bf5f7ead604e3cc0c8b0