Improve top(1) compatibility and interactive usefulness.

The toolbox -t option is really the standard -H option. Add -H so
I can switch dumpstate over.

We should also flush after each run so we don't arbitrarily truncate
at the stdio buffer size. (I'm pretty sure no one uses toolbox top
interactively, but it annoyed me while testing -H.)

Change-Id: Ib87cb541d1b21c48468614b2ef60b0cc62694c95