printsock: fix zero padding of sockaddr buffer
printsock: fix zero padding of sockaddr buffer

Before this change printsock used to erroneously clear the last byte
of sockaddr buffer.

* net.c (printsock): Use struct sockaddr_storage as a sockaddr buffer.
Reserve additional byte after the sockaddr buffer for zero padding.
Do not clear memory that is going to be overwritten by umoven.
Clear the tail of sockaddr buffer that was not overwritten by umoven.

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