EpollDatagramChannel avoid getOption

Motivation:
EpollDatagramChannel uses getOption in the isActive method. getOption is backed by a relatively large conditional if/else if block and this conditional checking can be avoided in the epoll transport.

Modifications:
- Add EpollDatagramChannelConfig#getActiveOnOpen and use this in EpollDatagramChannel

Result:
Conditional checking due to getOption is removed from EpollDatagramChannel.

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollDatagramChannel.java

@@ -21,7 +21,6 @@ import io.netty.buffer.CompositeByteBuf;
 import io.netty.channel.AddressedEnvelope;
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.ChannelMetadata;
-import io.netty.channel.ChannelOption;
 import io.netty.channel.ChannelOutboundBuffer;
 import io.netty.channel.ChannelPipeline;
 import io.netty.channel.ChannelPromise;
@@ -105,9 +104,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
     @Override
     @SuppressWarnings("deprecation")
     public boolean isActive() {
-        return fd().isOpen() &&
-                (config.getOption(ChannelOption.DATAGRAM_CHANNEL_ACTIVE_ON_REGISTRATION) && isRegistered()
-                        || active);
+        return fd().isOpen() && (config.getActiveOnOpen() && isRegistered() || active);
     }
 
     @Override

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollDatagramChannelConfig.java

@@ -132,6 +132,10 @@ public final class EpollDatagramChannelConfig extends EpollChannelConfig impleme
         this.activeOnOpen = activeOnOpen;
     }
 
+    boolean getActiveOnOpen() {
+        return activeOnOpen;
+    }
+
     @Override
     public EpollDatagramChannelConfig setMessageSizeEstimator(MessageSizeEstimator estimator) {
         super.setMessageSizeEstimator(estimator);