I've worked with a few other profilers than profiler.el so far and one
striking difference is that they allowed you to start a profiling run,
stop it and then retrieve the profiling log between these two points in
time.  profiler.el on the other hand flatout refuses to display a report
after stopping which is especially puzzling given the `profiler-stop`
docstring: "Stop started profilers.  Profiler logs will be kept."  If
the logs are kept after all, why can't I take a look at them?

I've attached a patch that solves this by caching the last accessable
profiler log.  This allows both workflows to work, be it displaying a
report while the profiler is still running or displaying it after
stopping the profiler.