Utils: Add ordNub
Utils: Add ordNub

For n*log(n) duplicate removal (as opposed to nub's n^2).

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

Cherry-picked-from: 5dd8067d
Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

yiannist/ganeti,mbakke/ganeti,mbakke/ganeti,yiannist/ganeti,onponomarev/ganeti,ganeti/ganeti,andir/ganeti,bitemyapp/ganeti,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,ganeti/ganeti,mbakke/ganeti,leshchevds/ganeti,andir/ganeti,bitemyapp/ganeti,leshchevds/ganeti,onponomarev/ganeti,ganeti/ganeti