Fix NoClassDefFoundError when netty-tcnative is unavailable

Motivation:

ProxyHandlerTest fails with NoClassDefFoundError raised by
SslContext.newClientContext().

Modifications:

Fix a missing 'return' statement that makes the switch-case block fall
through unncecessarily

Result:

- ProxyHandlerTest does not fail anymore.
- SslContext.newClientContext() does not raise NoClassDefFoundError
  anymore.

handler/src/main/java/io/netty/handler/ssl/SslContext.java

@@ -649,12 +649,12 @@ public abstract class SslContext {
         }
         switch (provider) {
             case JDK:
-                new JdkSslClientContext(trustCertChainFile, trustManagerFactory, keyCertChainFile, keyFile, keyPassword,
-                    keyManagerFactory, ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout);
+                return new JdkSslClientContext(
+                        trustCertChainFile, trustManagerFactory, keyCertChainFile, keyFile, keyPassword,
+                        keyManagerFactory, ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout);
             case OPENSSL:
                 return new OpenSslClientContext(
-                        trustCertChainFile, trustManagerFactory,
-                        ciphers, apn, sessionCacheSize, sessionTimeout);
+                        trustCertChainFile, trustManagerFactory, ciphers, apn, sessionCacheSize, sessionTimeout);
         }
         // Should never happen!!
         throw new Error();