tests: make test-bdiff.py easier to maintain Add more stdout logging to help navigate the .out file.

perf: unbust perfbdiff --alldata This broke in f84fc6a92817 due to a refactored manifest API. The fix is a bit hacky - perfbdiff doesn't yet support tree manifests for example. But it gets the job done. A test has been added for --alldata so this doesn't happen again.

worker: discard waited pid by anyone who noticed it first This makes sure all waited pids are removed before calling killworkers() even if waitpid()-pids.discard() sequence is interrupted by another SIGCHLD.