_dbus_append_address_from_socket: Correct misleading error message

If what actually failed was reading the address from the socket,
we might as well say so.

Signed-off-by: Simon McVittie <smcv@collabora.com>
Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=61922

dbus/dbus-sysdeps-unix.c

@@ -4742,7 +4742,7 @@ _dbus_append_address_from_socket (DBusSocket  fd,
  err:
   dbus_set_error (error,
                   _dbus_error_from_errno (errno),
-                  "Failed to open socket: %s",
+                  "Failed to read address from socket: %s",
                   _dbus_strerror (errno));
   return FALSE;
 }