ART: Add exit-code option to signal_dumper

To work around a corner-case behavioral difference in toybox timeout,
add an option to define the exit code on timeout.

Use this for target run-tests.

Bug: 140935398
Bug: 141007616
Test: manual
Change-Id: I4c5a93007af58861ede66dc376571a0fbefa38fa
2 files changed