Expand crasher with a "thread-" prefix to crash on another thread.

So "thread-nostack" runs the "nostack" code on a new thread, and
"thread-abort" runs the "abort" code on a new thread, and so on.

Bug: http://code.google.com/p/android/issues/detail?id=16672
Change-Id: I026a0e43eea147f1a7a74243846954599bcf4238