Added unit tests for register read (should pass) and the expression interpreter (xfail) after the inferior has crashed.
- Thanks to Samuel Jacob for the related reproducer.

Reviewed by: Daniel Malea.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@179788 91177308-0d34-0410-b5e6-96231b3b80d8