Make netty-transport-native-epoll-*-linux-x86_64.jar working in OSGi

Motivation:

Currenlty, netty-transport-native-epoll-*-linux-x86_64.jar is not packed as OSGi bundle
and thus not working in OSGi environment.

Modifications:

In netty-transport-native-epoll's pom.xml added configuration
to attach manifest to the jar with a native library.
In netty-common's pom.xml added configuration instruction (DynamicImport-Package)
to maven bnd plugin to make sure the native code is loaded from
netty-transport-native-epoll bundle.

Result:

The netty-transport-native-epoll-*-linux-x86_64.jar is a bundle (MANIFEST.MF attached)
and the inluced native library can be successfuly loaded in OSGi environment.
Fixing #5119

common/pom.xml

@@ -138,6 +138,27 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.felix</groupId>
+        <artifactId>maven-bundle-plugin</artifactId>
+        <version>2.4.0</version>
+        <executions>
+          <execution>
+            <id>generate-manifest</id>
+            <phase>process-classes</phase>
+            <goals>
+              <goal>manifest</goal>
+            </goals>
+            <configuration>
+              <instructions>
+                <!-- NativeLibraryLoader can be used to manually load native libraries from other bundles that this bundle does not depend on,
+                hence use DynamicImport-Package instruction to ensure the loading is successful -->
+                <DynamicImport-Package>*</DynamicImport-Package>
+              </instructions>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 </project>

transport-native-epoll/pom.xml

@@ -105,6 +105,13 @@
               <goal>jar</goal>
             </goals>
             <configuration>
+              <archive>
+                <manifest>
+                  <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
+                </manifest>
+                <index>true</index>
+                <manifestFile>${project.build.outputDirectory}/META-INF/MANIFEST.MF</manifestFile>
+              </archive>
               <classifier>${epoll.classifier}</classifier>
             </configuration>
           </execution>