Make also the features of the association 64-bit.
When exporting to xinpcb, just export the lower
32-bit. Using there also 64-bits will break the
ABI and will be committed separetly.

MFC after: 2 weeks
X-MFC with: 254248
Rename definition of HYPERVISOR_VIRT_START to avoid conflict with
upstream Xen definition found in xen/interface/arch-x86/xen-x86_32.h.

Submitted by:	Roger Pau Monné
Reviewed by:	gibbs
MFC after:	2 weeks