virDomainGetInfo returns a false result on IA64 systems

[Philippe Berthault <Philippe.Berthault@xxxxxxxx>]

The maxMem and memory fields of the virDomainInfo structure are false on 
IA64 systems.

The problem is in xen_internal.c at lines 1530,1531:
   info->memory = XEN_GETDOMAININFO_TOT_PAGES(dominfo) * 4;
   info->maxMem = XEN_GETDOMAININFO_MAX_PAGES(dominfo) * 4;

It's assumed that page size is 4 KB (* 4) but this isn't correct on a 
IA64 system where the page size is variable.

I haven't checked but I suppose this bug exists also with the 
virDomainGetMaxMemory and virDomainSetMaxMemory functions.

Regards.