tools: Synchronize privcmd header constants

tools: Synchronize privcmd header constants

Since Linux's git commit ceb90fa0a8008059ecbbf9114cb89dc71a730bb6,
the privcmd.h interface between Linux and libxc specifies two new
constants, PRIVCMD_MMAPBATCH_MFN_ERROR and
PRIVCMD_MMAPBATCH_PAGED_ERROR. These constants represent the error
codes encoded in the top nibble of an mfn slot passed to the legacy
MMAPBATCH ioctl.

In particular, libxenctrl checks for the equivalent of the latter
constant when dealing with paged out frames that might be the target
of a foreign map.

Previously, the relevant constant was defined in the domctl hypervisor
interface header (XEN_DOMCTL_PFINFO_PAGEDTAB). Because this
top-nibble encoding is a contract between the dom0 kernel and libxc,
a domctl.h definition is misplaced.

- Sync the privcmd.h header to that now available in upstream Linux
- Update libxc appropriately
- Remove the unnecessary constant in domctl.h

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Ian Campbell <ian.campbelL@citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>