event/ServerSocket, doc, ...: refer to AF_LOCAL as "local socket"

.. and not "UNIX domain socket.  Be consistent about the naming.

src/net/SocketUtil.hxx

@@ -32,7 +32,7 @@ class SocketAddress;
 /**
  * Creates a socket listening on the specified address.  This is a
  * shortcut for socket(), bind() and listen().
- * When a unix socket is created (domain == AF_UNIX), its
+ * When a local socket is created (domain == AF_LOCAL), its
  * permissions will be stripped down to prevent unauthorized
  * access. The caller is responsible to apply proper permissions
  * at a later point.