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505dc83f11dbc14d6e493d83ed6451966629fe71 by Evan Brown <ezb@google.com>:

In debug mode, make b-tree adapt comparators to do checking to diagnose invalid non-strict-weak-ordering comparators.

Reference: https://en.cppreference.com/w/cpp/named_req/Compare

- Add an opt-out mechanism for tests that rely on counting the number of comparisons.
- Use the unadapted comparator (original_key_compare) in making the use_linear_search decision so is_same still works.

PiperOrigin-RevId: 423889350
GitOrigin-RevId: 505dc83f11dbc14d6e493d83ed6451966629fe71
Change-Id: I65b0ba489c69c8dcfb107684db84f3f7f4d72daa