Construct a demonstration program for breakpoints and symbolic debugging

[travitch]

I'd like to come up with a relatively small C program that we can use to motivate our debugger development. We can track ideas for what it should look like in this thread. At a high level, I think it should probably:

• Have a non-obvious flaw that causes crux to not terminate while symbolically executing
• Motivate the ability to inspect the loop predicate in the debugger (where we can inspect it and identify the reason for the non-termination)