ART: Experiment with timeout dumping

In an attempt to diagnose some timeout dumping issues, allow a recursive
unexpected signal. Also print the new signal number irrespectively.

Test: m test-art-host
Test: manual: send timeout signal to run-test
Test: manual: send timeout signal to run-test, then send sigbus to run-test
Change-Id: Idf198b264a7e5868bdf444f323921c946584c650