Patch from Andreas Gruenbacher <agruen@suse.de>

This patch adds trusted extended attributes.  Trusted extended attributes are
visible and accessible only to processes that have the CAP_SYS_ADMIN
capability.  Attributes in this class are used to implement mechanisms in
user space (i.e., outside the kernel) which keep information in extended
attributes to which ordinary processes have no access.  HSM is an example.