The APIs for the two-range `absl::c_mismatch`, `absl::c_swap_ranges`,
and `absl::c_transform` are misleading as they do not check the bounds
of the second range against the first one.
This commit cleans up ensures that buggy calls are not exploitable;
non-buggy calls are unaffected.
This is consistent with both C++14's two-range `std::` equivalents and
C++20's `std::ranges::` equivalents.
http://wg21.link/mismatchhttp://wg21.link/alg.swaphttp://wg21.link/alg.transform
