Skip scanning rest of address if aldb_flag shows address not in use

MH dumps addresses not in use already, but continues to send 7 peek messages after discovering the address is not in use.  There is no need for this in the current code.  This should make scanning faster for those of us who add and delete links from our devices often.
Fix typos in fix for issue #46
Clean up coding mistake.  pending_aldb->address doesn't exist yet
Merge pull request #51 from krkeegan/fix_issue_46

Fix issue #46 - Stop Scanning Out of Use Entries

I have tested this for a few days and it is certainly faster, but for users with only a few empty addresses will see only slight speed increases.  I double checked and confirmed that MH has no code for enabling disabled links.