[3.12] gh-132075: Fix possible use of sockaddr structures with uninitialized members (GH-132076) (GH-132087)

Now all structure members are initialized with zeroes by default.
(cherry picked from commit 345baa77ba2ce3b8ea8f2fad84754e5cc0b10938)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>