Fix issue #3022508: Crash during media scan

Don't kill processes for excessive wake lock use, even if they
are in the background, as long as they have running services.

Also fix some problems with this, such as not noting the kill
in battery stats.

And add killing of processes for cpu usage as well, along with
some optimizations to computing CPU usage.

And fix BatteryWaster to be better behaving for testing these
cases.

Add new "monitor" command to am to watch as the activity manager
does stuff (so we can catch things at the point of ANR).

Finally some miscellaneous debug output for the stuff here, as
well as in progress debugging of an ANR.

Change-Id: Ib32f55ca50fb7486b4be4eb5e695f8f60c882cd1