fix(bhm): deliver exit signal reliably when component registration and signal submission coincide

> There's a race condition between the reception of
> `BackgroundHangMonitorControlMsg::Exit` and `MonitoredComponentMsg::
> Register`. When the worker receives `Exit`, it stops receiving
> messages, and any remaining messages (including the
> `MonitoredComponentMsg::Register` we sent) in the channel are dropped.
> Wrapping `exit_signal` with this RAII wrapper ensures the exit signal
> is delivered even in such cases.

This should (hopefully) eliminate the intermittent hang-ups in the test
case `test_hang_monitoring_exit_signal` for good.

0 files changed, 0 insertions, 0 deletions