scripts/headers_install.pl prevents "__user" from being exported
to userspace headers, so just use compiler.h to make sure that
__user is defined and avoid the error.

unifdef: linux-next-20101112/xx64/usr/include/xen/privcmd.h.tmp: 79: Premature EOF (#if line 33 depth 1)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc:	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc:	xen-devel@lists.xensource.com (moderated for non-subscribers)
Cc:	virtualization@lists.osdl.org
Cc:	Tony Finch <dot@dotat.at>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

The privcmd interface in xenfs allows the tool stack in the privileged
domain to get fairly direct access to the hypervisor in order to do
various management things such as domain construction.

[ Impact: new xenfs interface for privileged operations ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>