test/server: Use SO_REUSEADDR on listening sockets.
test/server: Use SO_REUSEADDR on listening sockets.

Make the TCP server example application enable SO_REUSEADDR on its
listening sockets to avoid the situation where binding its listening
sockets fails due to TIME_WAIT connections lingering around.

Signed-off-by: Lennert Buytenhek <8858498612e3a522354216649776e3032dcb7e5b@wantstofly.org>

buytenh/ivykis,buytenh/ivykis