selinux: Fix healthd's access to /dev nodes

Our healthd's support for power-on alarms adds some steps that imply
reading files its user doesn't own. Let it.

Change-Id: I3d4735aaab8fbec7acc460f812bc21f1dfa516ab
selinux: Add a rule to label the extended keyhandler dex files
These should be treated as regular dex cache files, but they're
expanded outside of the normal cache dir

Change-Id: Id046e1b90116b35d2e7817ed4717fcef78135f08