api.rseq test fails on AArch64

Migrating the AArch64 Jenkins CI to an Ampere Altera machine caused a regression in the api.rseq test with:

<Application /var/lib/jenkins/workspace/DynamoRIO-AArch64-Precommit/build/build_debug-internal-64/suite/tests/bin/api.rseq (247628). Failed to synchronize with all threads when detaching.>

But only the debug build. The release build passes.