Adds a test case for bugzilla #15671 patterned after TestInferiorCrashing.py.

- On Linux, the partial back-trace after an assert can cause the basic test to fail as discussed on lldb-dev.
- Uses SBFrame to walk up the stack to the assert site and tests expression evaluation of locals, globals and arguments.

Thanks to Daniel for review and testing on OS/X.

llvm-svn: 182115