Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1692

`optimization.h` uses `std::unreachable()` if available but does not include `<utility>`, causing errors in `absl/strings/ascii.cc`.
Merge bf912bb4e38341d6152ee145ec2be00251c42552 into 8a28a0c8

Merging this change closes #1692

COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1692 from poconn:optimization_missing_include bf912bb4e38341d6152ee145ec2be00251c42552
PiperOrigin-RevId: 645643983
Change-Id: I3966984afa81f2f6bce65dd872d326f0af114bfa