Tweak development settings to report system property changes.

Uses the new IBinder hack to tell all registered system services
about the property change.  This should get most processes of
interest...  some of them many times over, even.

This implementation does the broadcast for every debug property
change, though currently the only ones handling it are the
trace and layout bounds debugging properties.

Change-Id: Ibe3a10a40184751b8b2ed00021a224182d8f3f30