AsyncRpcClient test cases failure in powerpc

The new AsyncRpcClient feature added through the jira defect HBASE-12684 causing some test cases failures in powerpc64 environment.
I am testing it in master branch.

Looks like the version of netty (4.0.23) doesn't provide a support for non amd64 platforms and suggested to use pure java netty
Here is the discussion on that https://github.com/aphyr/riemann/pull/508

So new Async test cases will fail in ppc64 and other non amd64 platforms too.

Here is the output of the error.
Running org.apache.hadoop.hbase.ipc.TestAsyncIPC
Tests run: 24, Failures: 0, Errors: 6, Skipped: 0, Time elapsed: 2.802 sec <<< FAILURE! - in org.apache.hadoop.hbase.ipc.TestAsyncIPC
testRTEDuringAsyncConnectionSetup[3](org.apache.hadoop.hbase.ipc.TestAsyncIPC) Time elapsed: 0.048 sec <<< ERROR!
java.lang.UnsatisfiedLinkError: /tmp/libnetty-transport-native-epoll4286512618055650929.so: /tmp/libnetty-transport-native-epoll4286512618055650929.so: cannot open shared object file: No such file or directory (Possible cause: can't load AMD 64-bit .so on a Power PC 64-bit platform)
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1965)