Add flush to output to try to diagnose locks failure
Add flush to output to try to diagnose locks failure

end_to_end_test.py started failing after landing
https://codereview.chromium.org/1392093003/ but I'm not sure why. It
seems
https://build.chromium.org/p/client.crashpad/builders/crashpad_win_x64_dbg/builds/45/steps/run%20tests/logs/stdio
to be aborting in a place that doesn't make much sense, so try adding
flushes to see if there's output getting lost.

R=mark@chromium.org

Review URL: https://codereview.chromium.org/1410633002 .

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