Add a function computing the test instances
Add a function computing the test instances

The allocation vector (and hence the lost-allocations metrics build
on top of it) is based on counting how many instances of a certain
size can be placed on a node. Add a function computing those test
instances from the policy, i.e., add a returning an instance matching
the lower bounds of each policy interval, in decreasing order.

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

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