cabal repl use needs to restart the count

[shapr]

Because the RTS only counts up for regions executed, kudzu appears to do nothing after multiple runs in cabal repl

suggestion: zero the HPC counters?

[shapr]

After discussion with @JoshMeredith about path dependence, I think it makes more sense to save and clear the HPC values before a test run, and then restore the values after the run.