Fix s_client crash where the hostname is provided as a positional arg

If the hostname is provided as a positional arg then s_client crashes.
The crash occurs as s_client exits (after either a successful or
unsuccessful connection attempt).

This issue was introduced by commit 729ef856

.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3881)