If a process is failing due to out of memory, some code calls
android_set_abort_message with a nullptr. Specifically, the libc++
library std::terminate can call do this. In this case, put a
null in the abort message.
Test: Call with nullptr and verify the code does not crash.
Test: Modified crasher to set an abort message and set a null abort
Test: message. Ran both, verified the abort message displays in
Test: first case, and doesn't display in the second case.
Change-Id: Ia9250f47e4537853ce93bbb20b35915a78caa502
