add SunOS support

[cgrzemba]

This adds basic SunOS support tested on Illumos. Currently the NetworkAddressMonitor do not do dynamic network interface updates. The SMF manifest is not contained.

[christgau]

@cgrzemba I refactored the interface enumeration code a little. Could you please check if it still works.

I removed the cleanup routine as there was no work in the class to be done, i.e. there is no socket to be closed or removed from event handling. In addition, I assume that freeifaddrs can be called directly after the enumeration. Would be happy, if you can confirm (I do not have a SunOS/Illumos installation available nor I am familiar)

[cgrzemba]

There is an general issue with freeifaddrs so I do an explicit freeing like recommended here
https://stackoverflow.com/questions/60843140/ctypes-how-to-pass-struct-by-reference

[cgrzemba]

Should I merge the commits and do an forced update?

[christgau]

I added freeing the returned interface address list when enumeration was successful. If that looks good, I'll go ahead and merge

[cgrzemba]

Because freeipaddr of libc ends in core I replace the function with a equivalent function in Python

[cgrzemba]

The first option, freeing immediate after use, would also work.

[christgau]

The first option, freeing immediate after use, would also work.

Would be preferred, from my side,

In addition, I wonder what the socket is used for: https://github.com/cgrzemba/wsdd/blob/6a6f76da8f1f2abd328dda7a2395f775baa4e457/src/wsdd.py#L1795

[cgrzemba]

Thanks! I am fine with this code cleanup.