Make hcheck also check global N+1 redundancy
Make hcheck also check global N+1 redundancy

In the presence of shared storage, global N+1 redundancy has
to be checked. Therefore, make hcheck report the number of nodes
with instances that cannot immediately be restarted in case
of node failure.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

yiannist/ganeti,leshchevds/ganeti,yiannist/ganeti,yiannist/ganeti,ganeti/ganeti,leshchevds/ganeti,leshchevds/ganeti,mbakke/ganeti,ganeti/ganeti,onponomarev/ganeti,andir/ganeti,ganeti/ganeti,mbakke/ganeti,grnet/snf-ganeti,andir/ganeti,onponomarev/ganeti,andir/ganeti,mbakke/ganeti,bitemyapp/ganeti,dimara/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,dimara/ganeti