capabilities: allow nice if we are privileged
capabilities: allow nice if we are privileged

We allow task A to change B's nice level if it has a supserset of
B's privileges, or of it has CAP_SYS_NICE.  Also allow it if A has
CAP_SYS_NICE with respect to B - meaning it is root in the same
namespace, or it created B's namespace.

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@canonical.com>
Reviewed-by: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>
Signed-off-by: Eric W. Biederman <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs