static_signal failing with timeout or strange output (non-det)

[derekbruening]

Failed once on CDash:

http://dynamorio.org/CDash/testDetails.php?test=168921&build=15987

Required regular expression not found.Regex=[^Sending SIGUSR1 pre-DR-init
Got SIGUSR1
pre-DR init
in dr_client_main
Sending SIGUSR1 pre-DR-start
Got SIGUSR1
pre-DR start
Sending SIGUSR1 under DR
Got SIGUSR1
pre-DR stop
Saw some bb events
Saw 1 signal\(s\)
Sending SIGUSR1 post-DR-stop
Got SIGUSR1
all done
$
]

Test output
Sending SIGUSR1 pre-DR-init
Got SIGUSR1
pre-DR init
in dr_client_main
Sending SIGUSR1 pre-DR-start
Got SIGUSR1
pre-DR start
Sending SIGUSR1 under DR
Got SIGUSR1
Saw some bb events
Saw 2 signal(s)

[derekbruening]

Failed on Travis: https://travis-ci.org/DynamoRIO/dynamorio/jobs/216403717

[derekbruening]

I believe the recent Travis failures are not from the original code and thus the original CDash issue filed here but from the failure to see any alarm signals from d6d4faa417f5dc7b78c574bc5517d95ab33bfa3c which did not provide any guarantee that they'd be hit.

[dolanzhao]

The PR https://github.com/DynamoRIO/dynamorio/pull/5555 failed to pass the api.static_signal test on CI AArch64 too. http://139.178.82.61:8080/job/DynamoRIO-AArch64-Precommit/1783/consoleFull