Fix JRuby SSL connection failure: use SSLContext#setup instead of freeze

[idahomst]

Summary

On JRuby, OpenSSL::SSL::SSLContext#freeze causes a NullPointerException because the internal SSL engine (internalContext) is lazily initialized on the first connection attempt. Freezing the object beforehand prevents that lazy write, leaving internalContext null and breaking all SSL connections.

• Replace context.freeze with context.setup in build_ssl_ctx
• On CRuby, SSLContext#setup is effectively an alias for freeze — no behavioral change
• On JRuby (and other implementations), setup eagerly initializes the context without freezing, avoiding the NPE

Fixes #624

Co-authored-by: Nicholas Evans nevans@users.noreply.github.com

[nevans]

On JRuby (and other implementations), setup eagerly initializes the context without freezing

Not a big deal, but that's incorrect. JRuby's OpenSSL::SSL::SSLContext#setup also freezes the context, right at the end:

        try {
            internalContext = createInternalContext(context, cert, key, store, clientCert, extraChainCert,
                                                    verifyMode, timeout, alpnProtocols, alpnSelectCb);
        }
        catch (GeneralSecurityException e) {
            throw newSSLError(runtime, e);
        }
        // vvvvvvvvvvvvvvvvvv //
        this.freeze(context); // <-- right here 😉
        // ^^^^^^^^^^^^^^^^^^ //
        return runtime.getTrue();
    }