multiple tests (api.rseq, api.startstop, burst_threads, synch_attach) failed with "Failed to synchronize" on detach

**Describe the bug**

Seen in https://github.com/DynamoRIO/dynamorio/pull/5907
```
in event_post_attach
in event_pre_detach

```

**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**