x86 linux.signal0001 test failed with output ordering differences

Looks like non-deterministic output ordering. I don't think we've seen this before which is weird.

https://github.com/DynamoRIO/dynamorio/pull/5164/checks?check_run_id=3910404056

2021-10-15T21:06:08.1963378Z  46/356 Test  #45: code_api|linux.signal0001 ........................................***Failed  Required regular expression not found. Regex=[^Sending SIGUSR2
2021-10-15T21:06:08.1964069Z Sending SIGUSR1
2021-10-15T21:06:08.1964433Z in signal handler
2021-10-15T21:06:08.1964764Z Got SIGUSR1
2021-10-15T21:06:08.1965115Z Sending SIGRTMAX
2021-10-15T21:06:08.1965482Z in signal handler
2021-10-15T21:06:08.1965818Z Got SIGRTMAX
2021-10-15T21:06:08.1966182Z Generating SIGSEGV
2021-10-15T21:06:08.1966568Z in signal handler
2021-10-15T21:06:08.1966898Z Got SIGSEGV
2021-10-15T21:06:08.1967201Z 1750007\.722714
2021-10-15T21:06:08.1967531Z Got some timer hits!
2021-10-15T21:06:08.1967852Z $
2021-10-15T21:06:08.1968118Z ]  0.56 sec
2021-10-15T21:06:08.1968444Z Sending SIGUSR2
2021-10-15T21:06:08.1968805Z in signal handler
2021-10-15T21:06:08.1969138Z Got SIGUSR1
2021-10-15T21:06:08.1969483Z Sending SIGRTMAX
2021-10-15T21:06:08.1969851Z in signal handler
2021-10-15T21:06:08.1970185Z Got SIGRTMAX
2021-10-15T21:06:08.1970549Z Generating SIGSEGV
2021-10-15T21:06:08.1970929Z in signal handler
2021-10-15T21:06:08.1971269Z Got SIGSEGV
2021-10-15T21:06:08.1971558Z 1750007.722714
2021-10-15T21:06:08.1971887Z Got some timer hits!