Initial work on a Dumpstate class.

dumpstate used to be a C binary that had to be "converted" to C++ in
order to use the zip_writer library, but it still keeps most of its C
idioms.

This change is the first step towards a new Dumpstate class; for now, it
just moves the state defined on dumpstate.h to it.

BUG: 26379932
Test: manual / refactored code

Change-Id: Ie689b87c4469a8951c35f3e642d7faa0722b0c03
4 files changed