Remove several superuser capabilities from unconfined domains.

Remove sys_ptrace and add a neverallow for it.
Remove sys_rawio and mknod, explicitly allow to kernel, init, and recovery,
and add a neverallow for them.
Remove sys_module.  It can be added back where appropriate in device
policy if using a modular kernel.  No neverallow since it is device
specific.

Change-Id: I1a7971db8d247fd53a8f9392de9e46250e91f89b
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>