do reinstall binaries if their hash is not the expected

Closes: #5759

For this to work, the bundle needs to call::
``python setup.py hash_binaries`` during the bundling process, so that
the right hash gets updated in the bitmask/_binaries.py file.
Hmm I'm not sure a dialog box explaining that we didn't ship a proper bundle is needed, we should catch that before releasing. But okay, what should it say?