CAR-483: Check memory constraint only when the VM to migrate is live
CAR-483: Check memory constraint only when the VM to migrate is live

... as now we support XSM for halted or suspended VMs as well, which don't come
with memory constraint like live ones.

Signed-off-by: Zheng Li <34c6fceca75e456f25e7e99531e2425c6c1de443@zheng.li>

robertbreker/xen-api,vasilenkomike/xen-api,anoobs/xen-api,agimofcarmen/xen-api,guard163/xen-api,salvocambria/xen-api,anoobs/xen-api,djs55/xen-api,anoobs/xen-api,guard163/xen-api,jjd27/xen-api,agimofcarmen/xen-api,agimofcarmen/xen-api,thomassa/xen-api,euanh/xen-api,vasilenkomike/xen-api,djs55/xen-api,salvocambria/xen-api,robertbreker/xen-api,robertbreker/xen-api,robertbreker/xen-api,thomassa/xen-api,robertbreker/xen-api,vasilenkomike/xen-api,anoobs/xen-api,simonjbeaumont/xen-api,thomassa/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,Frezzle/xen-api,simonjbeaumont/xen-api,thomassa/xen-api,guard163/xen-api,Frezzle/xen-api,rafalmiel/xen-api,simonjbeaumont/xen-api,simonjbeaumont/xen-api,jjd27/xen-api,rafalmiel/xen-api,thomassa/xen-api,djs55/xen-api,jjd27/xen-api,vasilenkomike/xen-api,djs55/xen-api,euanh/xen-api,euanh/xen-api,euanh/xen-api,jjd27/xen-api,srowe/xen-api,anoobs/xen-api,srowe/xen-api,vasilenkomike/xen-api,guard163/xen-api,salvocambria/xen-api,Frezzle/xen-api,salvocambria/xen-api,simonjbeaumont/xen-api,salvocambria/xen-api,anoobs/xen-api,jjd27/xen-api,thomassa/xen-api,agimofcarmen/xen-api,guard163/xen-api,salvocambria/xen-api,agimofcarmen/xen-api,rafalmiel/xen-api,djs55/xen-api,srowe/xen-api,Frezzle/xen-api,jjd27/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api,simonjbeaumont/xen-api,vasilenkomike/xen-api,agimofcarmen/xen-api,djs55/xen-api,guard163/xen-api,srowe/xen-api,robertbreker/xen-api,rafalmiel/xen-api,euanh/xen-api