sio: fix error message displaying bind address

Now `sio_bind` function prints address into error message directly
instead of relying on `fd` used in `bind` that failed to execute.

`sio_bind` used `sio_socketname_to_buffer` for error message
effectively attempting printing address bound to `fd` while there
actually was an error in binding that address to that socket in the
first place.

Fixes #5925

NO_DOC=bugfix
NO_CHANGELOG=minor