Die with dignity on the network layer

When a fatal error is thrown on the network layer, such an error never
makes its way to the uncaught exception handler. This prevents the node
from being torn down if an out of memory error or other fatal error is
thrown while handling HTTP or transport traffic. This commit adds logic
to ensure that such errors bubble their way up to the uncaught exception
handler, even though Netty tries really hard to swallow everything.

Original commit: elastic/x-pack-elasticsearch@f76757674f

elasticsearch/src/main/java/org/elasticsearch/xpack/security/transport/netty4/SecurityNetty4HttpServerTransport.java

@@ -16,6 +16,7 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.http.netty4.Netty4HttpServerTransport;
 import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.transport.netty4.Netty4Utils;
 import org.elasticsearch.xpack.ssl.SSLService;
 import org.elasticsearch.xpack.security.transport.filter.IPFilter;
 
@@ -42,6 +43,7 @@ public class SecurityNetty4HttpServerTransport extends Netty4HttpServerTransport
 
     @Override
     protected void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
+        Netty4Utils.maybeDie(cause);
         if (!lifecycle.started()) {
             return;
         }