client.annotation-concurrency.prof-pcs.thread-private failing on Travis

edb2eed6 has introduced flakiness to test:

<Application /home/travis/build/DynamoRIO/dynamorio/build_debug-internal-64/suite/tests/bin/client.annotation-concurrency (23003).  Internal Error: DynamoRIO debug check failure: /home/travis/build/DynamoRIO/dynamorio/core/unix/signal.c:5248 dcontext == NULL || dcontext == GLOBAL_DCONTEXT || frame->uc.uc_stack.ss_sp == ((thread_sig_info_t *)dcontext->signal_field)->sigstack.ss_sp
(Error occurred @3403 frags)

Seems to be related to the new TLS magic check.