fa1b4e5c32 Use steady clock in FlushStateToDisk (MarcoFalke)
1111e2f8b4 Use steady clock in SeedStrengthen and FindBestImplementation (MarcoFalke)
Pull request description:
There may be a theoretical deadlock for the duration of the offset when the system clock is adjusted into a past time while executing `SeedStrengthen`.
Fix this by using steady clock.
Do the same in `FindBestImplementation`, which shouldn't be affected, because it discards outlier measurements. However, doing the same there for consistency seems fine.
Do the same in `FlushStateToDisk`, which should make the flushes more steady, if the system clock is adjusted by a large offset.
ACKs for top commit:
john-moffett:
ACK fa1b4e5c32
willcl-ark:
ACK fa1b4e5c3
Tree-SHA512: cc625e796b186accd53222bd64eb57d0512bc7e588312d254349b542bbc5e5daac348ff2b3b3f7dc5ae0bbbae2ec11fdbf3022cf2164211633765a4b0108e83e
2de0559f2c