fa521c9603 Use steady clock for all millis bench logging (MacroFake)
Pull request description:
Currently `GetTimeMillis` is used for bench logging in milliseconds integral precision. Replace it to use a steady clock that is type-safe and steady.
Microsecond or float precision can be done in a follow-up.
ACKs for top commit:
fanquake:
ACK fa521c9603 - started making the same change.
Tree-SHA512: 86a810e496fc663f815acb8771a6c770331593715cde85370226685bc50c13e8e987e3c5efd0b4e48b36ebd2372255357b709204bac750d41e94a9f7d9897fa6