If a Device lacks ifName, an alternative field is not always found even if available

[cigamit]

Describe the bug
The Interface ifName is the default sort order, when attempting to re-index a device, but in a case where the ifName returns no data, Cacti still attempts to use it as the correct first index, which is invalid

To Reproduce
Steps to reproduce the behavior:

1. Create a fake OID call ifPurple
2. Associate it with an OID that does not exit
3. Add if Purple to the <index_order> XML at the front
4. Re-index and the primary sort is not changed to the next available sort field.

Expected behavior
Cacti should properly cycle through all sort fields until it finds an acceptable sort order field.

[cigamit]

Resolved.