adb: add test for SIGHUP behavior.

This keeps regressing, so add a test to keep this from happening.

Bug: http://b/23603716
Bug: http://b/25965770
Bug: http://b/29565233
Test: Ran test with/without commit cd5d737, fails before, passes after
Change-Id: I8c431e10fc76da5a9fd404dd70f17bb8a8df24e6
1 file changed