Add setsockopt implementation

This is called by httpserver, and also the ssl support in the core
assumes that any socket object provides setsockopt (it passes along
calls on wrapped sockets, but eagerly fetches the "setsockopt" property
on construction of the SSL wrapper object)

adafruit_wiznet5k/adafruit_wiznet5k_socket.py

@@ -152,6 +152,9 @@ def inet_ntoa(ip_address: Union[bytes, bytearray]) -> str:
 
 _SOCKET_TYPE_TO_WIZNET = b"\0\x21\2"
 
+SOL_SOCKET = 0xFFF
+SO_REUSEADDR = 0x0004
+
 AF_INET = const(3)
 _SOCKET_INVALID = const(255)
 
@@ -682,6 +685,20 @@ def _available(self) -> int:
             self._socknum, _SOCKET_TYPE_TO_WIZNET[self._sock_type]
         )
 
+    @_check_socket_closed
+    def setsockopt(  # pylint: disable=no-self-use
+        self, level: int, opt: int, value: any
+    ) -> None:
+        """
+        Set a socket option.
+
+        Only SOL_SOCKET SO_REUSEADDR is accepted (and the value is ignored).
+
+        Other calls result in OSError."""
+        if level == SOL_SOCKET and opt == SO_REUSEADDR:
+            return
+        raise OSError
+
     @_check_socket_closed
     def settimeout(self, value: Optional[float]) -> None:
         """