Add netty-tcnative dependency to netty-example

Motivation:

It's useful to have netty-tcnative dependency in netty-example because
we can play with OpenSslEngine from our IDE.

Modifications:

Add netty-tcnative to example/pom.xml

example/pom.xml

@@ -62,6 +62,11 @@
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
     </dependency>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>netty-tcnative</artifactId>
+      <classifier>${os.detected.classifier}</classifier>
+    </dependency>
     <dependency>
       <groupId>com.jcraft</groupId>
       <artifactId>jzlib</artifactId>