api.startstop failing with "Failed to synchronize" on detach on x86-32

[prasun3]

Describe the bug

Seen in #5907

in event_post_attach
in event_pre_detach
<Application /home/pratn/dynamorio-latest/build-x86-32/suite/tests/bin/api.startstop (124291). Failed to synchronize with all threads when detaching.>

To Reproduce
Run suite/tests/bin/api.startstop

Expected behavior

Screenshots or Pasted Text

Versions

• What version of DynamoRIO are you using?
• Does the latest build from https://github.com/DynamoRIO/dynamorio/releases solve the problem?
• What operating system version are you running on? ("Windows 10" is not sufficient: give the release number.)
  • Linux
• Is your application 32-bit or 64-bit?
  • 32-bit

Additional context

[derekbruening]

There are other issues on startstop test failures (#4604, #2093, #2246) so I added the precise failure reason to the title here.