ART: Check for signal_dumper on-device for run-test

Check for the testing APEX, and fall back to PATH.

Bug: 138868214
Test: art/test/run-test --dev 001-HelloWorld
Test: manual (add signal_dumper)
Change-Id: Iab74fd94bd22520aa1de89426a5cba60cad21ee9
1 file changed