By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Fix race condition in mutation log output by using block buffering Set stderr to BlockBuffering so each hPutStr call writes the full multi-line mutation log entry as a single atomic syscall, preventing interleaved output from concurrent mutation threads. Also update the defaultSettings golden file with the two new settings fields added in a previous commit.
| Time to Start | Worker time | Duration | Time to finish | Idle | |
| Config | 0s | 2s | 2s | 2s | 0s |
| Eval | 3s | 36s | 36s | 39s | 0s |
| Build | 6s | 54s | 38s | 44s | 0s |
| Suite | 0s | 1m34s | 44s | 44s | 0s |