fail/cpn: removed USE_SIZE_PREFIX from SocketComm

This removes the ability to directly parse protobufs from the socket, because
google::protobuf::Message::ParseFromFileDescriptor() needs a EOF after each message;
thus preventing us from sending multiple Message objects over a single socket.

Change-Id: I67c0f631071470d6e0ae597e42848036a6db3656

src/core/comm/SocketComm.hpp

@@ -15,8 +15,6 @@
 #include <fstream>
 #include <google/protobuf/message.h>
 
-#define USE_SIZE_PREFIX
-
 namespace fail {
 
 class SocketComm {