Fix regression which lead to leak buffers when nothing could be read from the Channel.

This was introduced as part of #1812, but fortunatualy was not part of any release.

transport/src/main/java/io/netty/channel/nio/AbstractNioByteChannel.java

@@ -114,6 +114,8 @@ public abstract class AbstractNioByteChannel extends AbstractNioChannel {
                     byteBuf = allocHandle.allocate(allocator);
                     int localReadAmount = doReadBytes(byteBuf);
                     if (localReadAmount <= 0) {
+                        // not was read release the buffer
+                        byteBuf.release();
                         close = localReadAmount < 0;
                         break;
                     }