Update to the Xen-4.2 interface (deactived by #ifdefs)

We now have:
 * configurable xenstore and console backend domids
 * incrementable VM generation counts

This is all disabled by #ifdef XENGUEST_4_2 for now.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
If Xenctrl.domain_set_mmap_limit fails, log and continue

For an undiagnosed reason, this fails on xen-4.2

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Activate the new xen-4.2 interface.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Use #include <xenstore.h> since <xs.h> is now deprecated.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
[xenops]: plumb xenstore,console backend domids through domain build

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Remove unused Xenstore module dependencies

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>