Fix auto IP tracking

[shaxxx]

When auto IP function assigns new IP to existing edge node, it's current IP address is not updated. Which leads to duplicate IP's assigned when Pearson hash returns same value for two edge clients.

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.01% :warning:

Comparison is base (6b8ba8a) 21.67% compared to head (be9c31a) 21.66%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1142 +/- ## ========================================== - Coverage 21.67% 21.66% -0.01% ========================================== Files 46 46 Lines 8993 8996 +3 ========================================== Hits 1949 1949 - Misses 7044 7047 +3 ``` | [Files Changed](https://app.codecov.io/gh/ntop/n2n/pull/1142?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [src/sn\_utils.c](https://app.codecov.io/gh/ntop/n2n/pull/1142?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL3NuX3V0aWxzLmM=) | `0.00% <0.00%> (ø)` | |

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[hamishcoleman]

When you have finished your testing, mark this as ready for review and we will get it merged

[shaxxx]

Will do. So far it works fine, only change from previous version is there are no disconnected clients listed on the management port. Before, if clients did not make clean shutdown it's info would be still visible with last seen time somewhere in the past. Now, ali visible clients last seen time is within one minute. For me this is fantastic. Let's wait until Monday.

[shaxxx]

All good, ready for merge.